diff --git a/gridfs/__init__.py b/gridfs/__init__.py
index 8b13e0cb8..0edf03df5 100644
--- a/gridfs/__init__.py
+++ b/gridfs/__init__.py
@@ -125,7 +125,7 @@ class GridFS(object):
 
         return grid_file._id
 
-    def get(self, file_id):
+    def get(self, file_id, session=None):
         """Get a file from GridFS by ``"_id"``.
 
         Returns an instance of :class:`~gridfs.grid_file.GridOut`,
@@ -133,14 +133,19 @@ class GridFS(object):
 
         :Parameters:
           - `file_id`: ``"_id"`` of the file to get
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
-        gout = GridOut(self.__collection, file_id)
+        gout = GridOut(self.__collection, file_id, session=session)
 
         # Raise NoFile now, instead of on first attribute access.
         gout._ensure_file()
         return gout
 
-    def get_version(self, filename=None, version=-1, **kwargs):
+    def get_version(self, filename=None, version=-1, session=None, **kwargs):
         """Get a file from GridFS by ``"filename"`` or metadata fields.
 
         Returns a version of the file in GridFS whose filename matches
@@ -165,8 +170,13 @@ class GridFS(object):
           - `filename`: ``"filename"`` of the file to get, or `None`
           - `version` (optional): version of the file to get (defaults
             to -1, the most recent version uploaded)
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
           - `**kwargs` (optional): find files by custom metadata.
 
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
+
         .. versionchanged:: 3.1
            ``get_version`` no longer ensures indexes.
         """
@@ -174,19 +184,20 @@ class GridFS(object):
         if filename is not None:
             query["filename"] = filename
 
-        cursor = self.__files.find(query)
+        cursor = self.__files.find(query, session=session)
         if version < 0:
             skip = abs(version) - 1
             cursor.limit(-1).skip(skip).sort("uploadDate", DESCENDING)
         else:
             cursor.limit(-1).skip(version).sort("uploadDate", ASCENDING)
         try:
-            grid_file = next(cursor)
-            return GridOut(self.__collection, file_document=grid_file)
+            doc = next(cursor)
+            return GridOut(
+                self.__collection, file_document=doc, session=session)
         except StopIteration:
             raise NoFile("no version %d for filename %r" % (version, filename))
 
-    def get_last_version(self, filename=None, **kwargs):
+    def get_last_version(self, filename=None, session=None, **kwargs):
         """Get the most recent version of a file in GridFS by ``"filename"``
         or metadata fields.
 
@@ -195,12 +206,17 @@ class GridFS(object):
 
         :Parameters:
           - `filename`: ``"filename"`` of the file to get, or `None`
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
           - `**kwargs` (optional): find files by custom metadata.
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
-        return self.get_version(filename=filename, **kwargs)
+        return self.get_version(filename=filename, session=session, **kwargs)
 
     # TODO add optional safe mode for chunk removal?
-    def delete(self, file_id):
+    def delete(self, file_id, session=None):
         """Delete a file from GridFS by ``"_id"``.
 
         Deletes all data belonging to the file with ``"_id"``:
@@ -216,27 +232,39 @@ class GridFS(object):
 
         :Parameters:
           - `file_id`: ``"_id"`` of the file to delete
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
 
         .. versionchanged:: 3.1
            ``delete`` no longer ensures indexes.
         """
-        self.__files.delete_one({"_id": file_id})
-        self.__chunks.delete_many({"files_id": file_id})
+        self.__files.delete_one({"_id": file_id}, session=session)
+        self.__chunks.delete_many({"files_id": file_id}, session=session)
 
-    def list(self):
+    def list(self, session=None):
         """List the names of all files stored in this instance of
         :class:`GridFS`.
 
+        :Parameters:
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
+
         .. versionchanged:: 3.1
            ``list`` no longer ensures indexes.
         """
         # With an index, distinct includes documents with no filename
         # as None.
         return [
-            name for name in self.__files.distinct("filename")
+            name for name in self.__files.distinct("filename", session=session)
             if name is not None]
 
-    def find_one(self, filter=None, *args, **kwargs):
+    def find_one(self, filter=None, session=None, *args, **kwargs):
         """Get a single file from gridfs.
 
         All arguments to :meth:`find` are also valid arguments for
@@ -252,13 +280,18 @@ class GridFS(object):
             the value for a query for ``"_id"`` in the file collection.
           - `*args` (optional): any additional positional arguments are
             the same as the arguments to :meth:`find`.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
           - `**kwargs` (optional): any additional keyword arguments
             are the same as the arguments to :meth:`find`.
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         if filter is not None and not isinstance(filter, Mapping):
             filter = {"_id": filter}
 
-        for f in self.find(filter, *args, **kwargs):
+        for f in self.find(filter, *args, session=session, **kwargs):
             return f
 
         return None
@@ -290,6 +323,10 @@ class GridFS(object):
         :meth:`~pymongo.collection.Collection.find`
         in :class:`~pymongo.collection.Collection`.
 
+        If a :class:`~pymongo.client_session.ClientSession` is passed to
+        :meth:`find`, all returned :class:`~gridfs.grid_file.GridOut` instances
+        are associated with that session.
+
         :Parameters:
           - `filter` (optional): a SON object specifying elements which
             must be present for a document to be included in the
@@ -320,7 +357,7 @@ class GridFS(object):
         """
         return GridOutCursor(self.__collection, *args, **kwargs)
 
-    def exists(self, document_or_id=None, **kwargs):
+    def exists(self, document_or_id=None, session=None, **kwargs):
         """Check if a file exists in this instance of :class:`GridFS`.
 
         The file to check for can be specified by the value of its
@@ -350,12 +387,20 @@ class GridFS(object):
         :Parameters:
           - `document_or_id` (optional): query document, or _id of the
             document to check for
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
           - `**kwargs` (optional): keyword arguments are used as a
             query document, if they're present.
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         if kwargs:
-            return self.__files.find_one(kwargs, ["_id"]) is not None
-        return self.__files.find_one(document_or_id, ["_id"]) is not None
+            f = self.__files.find_one(kwargs, ["_id"], session=session)
+        else:
+            f = self.__files.find_one(document_or_id, ["_id"], session=session)
+
+        return f is not None
 
 
 class GridFSBucket(object):
@@ -409,7 +454,7 @@ class GridFSBucket(object):
         self._chunk_size_bytes = chunk_size_bytes
 
     def open_upload_stream(self, filename, chunk_size_bytes=None,
-                           metadata=None):
+                           metadata=None, session=None):
         """Opens a Stream that the application can write the contents of the
         file to.
 
@@ -439,6 +484,11 @@ class GridFSBucket(object):
           - `metadata` (optional): User data for the 'metadata' field of the
             files collection document. If not provided the metadata field will
             be omitted from the files collection document.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         validate_string("filename", filename)
 
@@ -448,10 +498,11 @@ class GridFSBucket(object):
         if metadata is not None:
             opts["metadata"] = metadata
 
-        return GridIn(self._collection, **opts)
+        return GridIn(self._collection, session=session, **opts)
 
     def open_upload_stream_with_id(
-            self, file_id, filename, chunk_size_bytes=None, metadata=None):
+            self, file_id, filename, chunk_size_bytes=None, metadata=None,
+            session=None):
         """Opens a Stream that the application can write the contents of the
         file to.
 
@@ -485,6 +536,11 @@ class GridFSBucket(object):
           - `metadata` (optional): User data for the 'metadata' field of the
             files collection document. If not provided the metadata field will
             be omitted from the files collection document.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         validate_string("filename", filename)
 
@@ -495,10 +551,10 @@ class GridFSBucket(object):
         if metadata is not None:
             opts["metadata"] = metadata
 
-        return GridIn(self._collection, **opts)
+        return GridIn(self._collection, session=session, **opts)
 
     def upload_from_stream(self, filename, source, chunk_size_bytes=None,
-                           metadata=None):
+                           metadata=None, session=None):
         """Uploads a user file to a GridFS bucket.
 
         Reads the contents of the user file from `source` and uploads
@@ -528,15 +584,21 @@ class GridFSBucket(object):
           - `metadata` (optional): User data for the 'metadata' field of the
             files collection document. If not provided the metadata field will
             be omitted from the files collection document.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         with self.open_upload_stream(
-                filename, chunk_size_bytes, metadata) as gin:
+                filename, chunk_size_bytes, metadata, session=session) as gin:
             gin.write(source)
 
         return gin._id
 
     def upload_from_stream_with_id(self, file_id, filename, source,
-                                   chunk_size_bytes=None, metadata=None):
+                                   chunk_size_bytes=None, metadata=None,
+                                   session=None):
         """Uploads a user file to a GridFS bucket with a custom file id.
 
         Reads the contents of the user file from `source` and uploads
@@ -567,12 +629,18 @@ class GridFSBucket(object):
           - `metadata` (optional): User data for the 'metadata' field of the
             files collection document. If not provided the metadata field will
             be omitted from the files collection document.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         with self.open_upload_stream_with_id(
-                file_id, filename, chunk_size_bytes, metadata) as gin:
+                file_id, filename, chunk_size_bytes, metadata,
+                session=session) as gin:
             gin.write(source)
 
-    def open_download_stream(self, file_id):
+    def open_download_stream(self, file_id, session=None):
         """Opens a Stream from which the application can read the contents of
         the stored file specified by file_id.
 
@@ -591,14 +659,19 @@ class GridFSBucket(object):
 
         :Parameters:
           - `file_id`: The _id of the file to be downloaded.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
-        gout = GridOut(self._collection, file_id)
+        gout = GridOut(self._collection, file_id, session=session)
 
         # Raise NoFile now, instead of on first attribute access.
         gout._ensure_file()
         return gout
 
-    def download_to_stream(self, file_id, destination):
+    def download_to_stream(self, file_id, destination, session=None):
         """Downloads the contents of the stored file specified by file_id and
         writes the contents to `destination`.
 
@@ -619,12 +692,17 @@ class GridFSBucket(object):
         :Parameters:
           - `file_id`: The _id of the file to be downloaded.
           - `destination`: a file-like object implementing :meth:`write`.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
-        gout = self.open_download_stream(file_id)
+        gout = self.open_download_stream(file_id, session=session)
         for chunk in gout:
             destination.write(chunk)
 
-    def delete(self, file_id):
+    def delete(self, file_id, session=None):
         """Given an file_id, delete this stored file's files collection document
         and associated chunks from a GridFS bucket.
 
@@ -640,9 +718,14 @@ class GridFSBucket(object):
 
         :Parameters:
           - `file_id`: The _id of the file to be deleted.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
-        res = self._files.delete_one({"_id": file_id})
-        self._chunks.delete_many({"files_id": file_id})
+        res = self._files.delete_one({"_id": file_id}, session=session)
+        self._chunks.delete_many({"files_id": file_id}, session=session)
         if not res.deleted_count:
             raise NoFile(
                 "no file could be deleted because none matched %s" % file_id)
@@ -676,6 +759,10 @@ class GridFSBucket(object):
         :meth:`~pymongo.collection.Collection.find`
         in :class:`~pymongo.collection.Collection`.
 
+        If a :class:`~pymongo.client_session.ClientSession` is passed to
+        :meth:`find`, all returned :class:`~gridfs.grid_file.GridOut` instances
+        are associated with that session.
+
         :Parameters:
           - `filter`: Search query.
           - `batch_size` (optional): The number of documents to return per
@@ -691,7 +778,7 @@ class GridFSBucket(object):
         """
         return GridOutCursor(self._collection, *args, **kwargs)
 
-    def open_download_stream_by_name(self, filename, revision=-1):
+    def open_download_stream_by_name(self, filename, revision=-1, session=None):
         """Opens a Stream from which the application can read the contents of
         `filename` and optional `revision`.
 
@@ -714,6 +801,8 @@ class GridFSBucket(object):
           - `revision` (optional): Which revision (documents with the same
             filename and different uploadDate) of the file to retrieve.
             Defaults to -1 (the most recent revision).
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
 
         :Note: Revision numbers are defined as follows:
 
@@ -723,12 +812,15 @@ class GridFSBucket(object):
           - etc...
           - -2 = the second most recent revision
           - -1 = the most recent revision
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         validate_string("filename", filename)
 
         query = {"filename": filename}
 
-        cursor = self._files.find(query)
+        cursor = self._files.find(query, session=session)
         if revision < 0:
             skip = abs(revision) - 1
             cursor.limit(-1).skip(skip).sort("uploadDate", DESCENDING)
@@ -736,12 +828,14 @@ class GridFSBucket(object):
             cursor.limit(-1).skip(revision).sort("uploadDate", ASCENDING)
         try:
             grid_file = next(cursor)
-            return GridOut(self._collection, file_document=grid_file)
+            return GridOut(
+                self._collection, file_document=grid_file, session=session)
         except StopIteration:
             raise NoFile(
                 "no version %d for filename %r" % (revision, filename))
 
-    def download_to_stream_by_name(self, filename, destination, revision=-1):
+    def download_to_stream_by_name(self, filename, destination, revision=-1,
+                                   session=None):
         """Write the contents of `filename` (with optional `revision`) to
         `destination`.
 
@@ -764,6 +858,8 @@ class GridFSBucket(object):
           - `revision` (optional): Which revision (documents with the same
             filename and different uploadDate) of the file to retrieve.
             Defaults to -1 (the most recent revision).
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
 
         :Note: Revision numbers are defined as follows:
 
@@ -773,12 +869,16 @@ class GridFSBucket(object):
           - etc...
           - -2 = the second most recent revision
           - -1 = the most recent revision
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
-        gout = self.open_download_stream_by_name(filename, revision)
+        gout = self.open_download_stream_by_name(
+            filename, revision, session=session)
         for chunk in gout:
             destination.write(chunk)
 
-    def rename(self, file_id, new_filename):
+    def rename(self, file_id, new_filename, session=None):
         """Renames the stored file with the specified file_id.
 
         For example::
@@ -794,9 +894,15 @@ class GridFSBucket(object):
         :Parameters:
           - `file_id`: The _id of the file to be renamed.
           - `new_filename`: The new name of the file.
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession`
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
         """
         result = self._files.update_one({"_id": file_id},
-                                        {"$set": {"filename": new_filename}})
+                                        {"$set": {"filename": new_filename}},
+                                        session=session)
         if not result.matched_count:
             raise NoFile("no files could be renamed %r because none "
                          "matched file_id %i" % (new_filename, file_id))
diff --git a/gridfs/grid_file.py b/gridfs/grid_file.py
index 390f8437e..5cc8f8faf 100644
--- a/gridfs/grid_file.py
+++ b/gridfs/grid_file.py
@@ -100,7 +100,7 @@ def _grid_out_property(field_name, docstring):
 class GridIn(object):
     """Class to write data to GridFS.
     """
-    def __init__(self, root_collection, **kwargs):
+    def __init__(self, root_collection, session=None, **kwargs):
         """Write a file to GridFS
 
         Application developers should generally not need to
@@ -136,8 +136,14 @@ class GridIn(object):
 
         :Parameters:
           - `root_collection`: root collection to write to
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession` to use for all
+            commands
           - `**kwargs` (optional): file level options (see above)
 
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
+
         .. versionchanged:: 3.0
            `root_collection` must use an acknowledged
            :attr:`~pymongo.collection.Collection.write_concern`
@@ -164,6 +170,7 @@ class GridIn(object):
         # Defaults
         kwargs["_id"] = kwargs.get("_id", ObjectId())
         kwargs["chunkSize"] = kwargs.get("chunkSize", DEFAULT_CHUNK_SIZE)
+        object.__setattr__(self, "_session", session)
         object.__setattr__(self, "_coll", coll)
         object.__setattr__(self, "_chunks", coll.chunks)
         object.__setattr__(self, "_file", kwargs)
@@ -174,14 +181,16 @@ class GridIn(object):
         object.__setattr__(self, "_ensured_index", False)
 
     def __create_index(self, collection, index_key, unique):
-        doc = collection.find_one(projection={"_id": 1})
+        doc = collection.find_one(projection={"_id": 1}, session=self._session)
         if doc is None:
             try:
-                index_keys =[index_spec['key'] for index_spec in collection.list_indexes()]
+                index_keys = [index_spec['key'] for index_spec in
+                              collection.list_indexes(session=self._session)]
             except OperationFailure:
                 index_keys = []
             if index_key not in index_keys:
-                collection.create_index(index_key.items(), unique=unique)
+                collection.create_index(
+                    index_key.items(), unique=unique, session=self._session)
 
     def __ensure_indexes(self):
         if not object.__getattribute__(self, "_ensured_index"):
@@ -192,11 +201,12 @@ class GridIn(object):
     def abort(self):
         """Remove all chunks/files that may have been uploaded and close.
         """
-        self._coll.chunks.delete_many({"files_id": self._file['_id']})
-        self._coll.files.delete_one({"_id": self._file['_id']})
+        self._coll.chunks.delete_many(
+            {"files_id": self._file['_id']}, session=self._session)
+        self._coll.files.delete_one(
+            {"_id": self._file['_id']}, session=self._session)
         object.__setattr__(self, "_closed", True)
 
-
     @property
     def closed(self):
         """Is this file closed?
@@ -255,7 +265,7 @@ class GridIn(object):
                  "data": Binary(data)}
 
         try:
-            self._chunks.insert_one(chunk)
+            self._chunks.insert_one(chunk, session=self._session)
         except DuplicateKeyError:
             self._raise_file_exists(self._file['_id'])
         self._chunk_number += 1
@@ -278,7 +288,8 @@ class GridIn(object):
             self._file["length"] = self._position
             self._file["uploadDate"] = datetime.datetime.utcnow()
 
-            return self._coll.files.insert_one(self._file)
+            return self._coll.files.insert_one(
+                self._file, session=self._session)
         except DuplicateKeyError:
             self._raise_file_exists(self._id)
 
@@ -382,7 +393,8 @@ class GridIn(object):
 class GridOut(object):
     """Class to read data out of GridFS.
     """
-    def __init__(self, root_collection, file_id=None, file_document=None):
+    def __init__(self, root_collection, file_id=None, file_document=None,
+                 session=None):
         """Read a file from GridFS
 
         Application developers should generally not need to
@@ -399,6 +411,12 @@ class GridOut(object):
           - `file_id` (optional): value of ``"_id"`` for the file to read
           - `file_document` (optional): file document from
             `root_collection.files`
+          - `session` (optional): a
+            :class:`~pymongo.client_session.ClientSession` to use for all
+            commands
+
+        .. versionchanged:: 3.6
+           Added ``session`` parameter.
 
         .. versionchanged:: 3.0
            Creating a GridOut does not immediately retrieve the file metadata
@@ -414,6 +432,7 @@ class GridOut(object):
         self.__buffer = EMPTY
         self.__position = 0
         self._file = file_document
+        self._session = session
 
     _id = _grid_out_property("_id", "The ``'_id'`` value for this file.")
     filename = _grid_out_property("filename", "Name of this file.")
@@ -430,7 +449,8 @@ class GridOut(object):
 
     def _ensure_file(self):
         if not self._file:
-            self._file = self.__files.find_one({"_id": self.__file_id})
+            self._file = self.__files.find_one({"_id": self.__file_id},
+                                               session=self._session)
             if not self._file:
                 raise NoFile("no file in gridfs collection %r with _id %r" %
                              (self.__files, self.__file_id))
@@ -454,7 +474,8 @@ class GridOut(object):
         elif self.__position < int(self.length):
             chunk_number = int((received + self.__position) / chunk_size)
             chunk = self.__chunks.find_one({"files_id": self._id,
-                                            "n": chunk_number})
+                                            "n": chunk_number},
+                                           session=self._session)
             if not chunk:
                 raise CorruptGridFile("no chunk #%d" % chunk_number)
 
@@ -496,7 +517,8 @@ class GridOut(object):
         # Detect extra chunks.
         max_chunk_n = math.ceil(self.length / float(self.chunk_size))
         chunk = self.__chunks.find_one({"files_id": self._id,
-                                        "n": {"$gte": max_chunk_n}})
+                                        "n": {"$gte": max_chunk_n}},
+                                       session=self._session)
         # According to spec, ignore extra chunks if they are empty.
         if chunk is not None and len(chunk['data']):
             raise CorruptGridFile(
@@ -585,7 +607,7 @@ class GridOut(object):
         useful when serving files using a webserver that handles
         such an iterator efficiently.
         """
-        return GridOutIterator(self, self.__chunks)
+        return GridOutIterator(self, self.__chunks, self._session)
 
     def close(self):
         """Make GridOut more generically file-like."""
@@ -605,9 +627,10 @@ class GridOut(object):
 
 
 class GridOutIterator(object):
-    def __init__(self, grid_out, chunks):
+    def __init__(self, grid_out, chunks, session):
         self.__id = grid_out._id
         self.__chunks = chunks
+        self.__session = session
         self.__current_chunk = 0
         self.__max_chunk = math.ceil(float(grid_out.length) /
                                      grid_out.chunk_size)
@@ -619,7 +642,8 @@ class GridOutIterator(object):
         if self.__current_chunk >= self.__max_chunk:
             raise StopIteration
         chunk = self.__chunks.find_one({"files_id": self.__id,
-                                        "n": self.__current_chunk})
+                                        "n": self.__current_chunk},
+                                       session=self.__session)
         if not chunk:
             raise CorruptGridFile("no chunk #%d" % self.__current_chunk)
         self.__current_chunk += 1
@@ -633,7 +657,8 @@ class GridOutCursor(Cursor):
     of an arbitrary query against the GridFS files collection.
     """
     def __init__(self, collection, filter=None, skip=0, limit=0,
-                 no_cursor_timeout=False, sort=None, batch_size=0):
+                 no_cursor_timeout=False, sort=None, batch_size=0,
+                 session=None):
         """Create a new cursor, similar to the normal
         :class:`~pymongo.cursor.Cursor`.
 
@@ -650,14 +675,15 @@ class GridOutCursor(Cursor):
         super(GridOutCursor, self).__init__(
             collection.files, filter, skip=skip, limit=limit,
             no_cursor_timeout=no_cursor_timeout, sort=sort,
-            batch_size=batch_size)
+            batch_size=batch_size, session=session)
 
     def next(self):
         """Get next GridOut object from cursor.
         """
         # Work around "super is not iterable" issue in Python 3.x
         next_file = super(GridOutCursor, self).next()
-        return GridOut(self.__root_collection, file_document=next_file)
+        return GridOut(self.__root_collection, file_document=next_file,
+                       session=self.session)
 
     __next__ = next
 
diff --git a/test/test_session.py b/test/test_session.py
index a1d462865..9f5bb1825 100644
--- a/test/test_session.py
+++ b/test/test_session.py
@@ -13,8 +13,11 @@
 # limitations under the License.
 
 """Test the client_session module."""
+
 from bson import DBRef
-from pymongo import InsertOne, IndexModel, monitoring, OFF
+from bson.py3compat import StringIO
+from gridfs import GridFS, GridFSBucket
+from pymongo import InsertOne, IndexModel, OFF, monitoring
 from pymongo.errors import (ConfigurationError,
                             InvalidOperation,
                             OperationFailure)
@@ -49,6 +52,27 @@ class TestSession(IntegrationTest):
         monitoring._SENSITIVE_COMMANDS.update(self.sensitive_commands)
         super(TestSession, self).tearDown()
 
+    def _test_ops(self, client, *ops):
+        listener = client.event_listeners()[0][0]
+
+        with client.start_session() as s:
+            for f, args, kwargs in ops:
+                listener.results.clear()
+                kwargs['session'] = s
+                f(*args, **kwargs)
+                self.assertGreaterEqual(len(listener.results['started']), 1)
+                for event in listener.results['started']:
+                    self.assertTrue(
+                        'lsid' in event.command,
+                        "%s sent no lsid with %s" % (
+                            f.__name__, event.command_name))
+
+                    self.assertEqual(
+                        s.session_id,
+                        event.command['lsid'],
+                        "%s sent wrong lsid with %s" % (
+                            f.__name__, event.command_name))
+
     @client_context.require_auth
     @ignore_deprecations
     def test_session_authenticate_multiple(self):
@@ -112,23 +136,7 @@ class TestSession(IntegrationTest):
                 (client.unlock, [], {}),
             ])
 
-        with client.start_session() as s:
-            for f, args, kwargs in ops:
-                listener.results.clear()
-                kwargs['session'] = s
-                f(*args, **kwargs)
-                self.assertGreaterEqual(len(listener.results['started']), 1)
-                for event in listener.results['started']:
-                    self.assertTrue(
-                        'lsid' in event.command,
-                        "%s sent no lsid with %s" % (
-                            f.__name__, event.command_name))
-
-                    self.assertEqual(
-                        s.session_id,
-                        event.command['lsid'],
-                        "%s sent wrong lsid with %s" % (
-                            f.__name__, event.command_name))
+        self._test_ops(client, *ops)
 
     @client_context.require_sessions
     def test_database(self):
@@ -161,23 +169,7 @@ class TestSession(IntegrationTest):
             ops.append((db.set_profiling_level, [OFF], {}))
             ops.append((db.profiling_level, [], {}))
 
-        with client.start_session() as s:
-            for f, args, kwargs in ops:
-                listener.results.clear()
-                kwargs['session'] = s
-                f(*args, **kwargs)
-                self.assertGreaterEqual(len(listener.results['started']), 1)
-                for event in listener.results['started']:
-                    self.assertTrue(
-                        'lsid' in event.command,
-                        "%s sent no lsid with %s" % (
-                            f.__name__, event.command_name))
-
-                    self.assertEqual(
-                        s.session_id,
-                        event.command['lsid'],
-                        "%s sent wrong lsid with %s" % (
-                            f.__name__, event.command_name))
+        self._test_ops(client, *ops)
 
     @client_context.require_sessions
     def test_collection(self):
@@ -290,3 +282,78 @@ class TestSession(IntegrationTest):
                         event.command['lsid'],
                         "%s sent wrong lsid with %s" % (
                             name, event.command_name))
+
+    @client_context.require_sessions
+    def test_gridfs(self):
+        listener = SessionTestListener()
+        client = rs_or_single_client(event_listeners=[listener])
+        client.drop_database('pymongo_test')
+        self.addCleanup(client.drop_database, 'pymongo_test')
+
+        fs = GridFS(client.pymongo_test)
+
+        def new_file(session):
+            grid_file = fs.new_file(_id=1, filename='f', session=session)
+            grid_file.write(b'a')
+            grid_file.close()
+
+        self._test_ops(
+            client,
+            (new_file, [], {}),
+            (fs.put, [b'data'], {}),
+            (lambda session: fs.get(1, session=session).read(), [], {}),
+            (lambda session: fs.get_version('f', session=session).read(),
+             [], {}),
+            (lambda session: fs.get_last_version('f', session=session).read(),
+             [], {}),
+            (fs.list, [], {}),
+            (fs.find_one, [1], {}),
+            (lambda session: list(fs.find(session=session)), [], {}),
+            (fs.exists, [1], {}),
+            (fs.delete, [1], {}))
+
+    @client_context.require_sessions
+    def test_gridfs_bucket(self):
+        listener = SessionTestListener()
+        client = rs_or_single_client(event_listeners=[listener])
+        client.drop_database('pymongo_test')
+        self.addCleanup(client.drop_database, 'pymongo_test')
+
+        bucket = GridFSBucket(client.pymongo_test)
+
+        def upload(session):
+            stream = bucket.open_upload_stream('f', session=session)
+            stream.write(b'a')
+            stream.close()
+
+        def upload_with_id(session):
+            stream = bucket.open_upload_stream_with_id(1, 'f1', session=session)
+            stream.write(b'a')
+            stream.close()
+
+        def open_download_stream(session):
+            stream = bucket.open_download_stream(1, session=session)
+            stream.read()
+
+        def open_download_stream_by_name(session):
+            stream = bucket.open_download_stream_by_name('f', session=session)
+            stream.read()
+
+        def find(session):
+            stream = bucket.find({'_id': 1}, session=session).next()
+            stream.read()
+
+        sio = StringIO()
+
+        self._test_ops(
+            client,
+            (upload, [], {}),
+            (upload_with_id, [], {}),
+            (bucket.upload_from_stream, ['f', 'data'], {}),
+            (bucket.upload_from_stream_with_id, [2, 'f', 'data'], {}),
+            (open_download_stream, [], {}),
+            (open_download_stream_by_name, [], {}),
+            (bucket.download_to_stream, [1, sio], {}),
+            (bucket.download_to_stream_by_name, ['f', sio], {}),
+            (find, [], {}),
+            (bucket.rename, [1, 'f2'], {}))