diff --git a/gridfs/__init__.py b/gridfs/__init__.py
index 5c9193938..2dc41be89 100644
--- a/gridfs/__init__.py
+++ b/gridfs/__init__.py
@@ -44,7 +44,11 @@ class GridFS(object):
         """Open a GridFile for reading or writing.
 
         Shorthand method for creating / opening a GridFile from a filename. mode
-        must be a mode supported by `gridfs.grid_file.GridFile`
+        must be a mode supported by `gridfs.grid_file.GridFile`.
+
+        Only a single opened GridFile instance may exist for a file in gridfs
+        at any time. Care must be taken to close GridFile instances when done
+        using them.
 
         :Parameters:
           - `filename`: name of the GridFile to open
diff --git a/gridfs/grid_file.py b/gridfs/grid_file.py
index a2612f6ca..63281f4cd 100644
--- a/gridfs/grid_file.py
+++ b/gridfs/grid_file.py
@@ -44,7 +44,11 @@ class GridFile(object):
         """Open a "file" in GridFS.
 
         Application developers should generally not need to instantiate this
-        class directly.
+        class directly - instead see the `gridfs.open` method.
+
+        Only a single opened GridFile instance may exist for a file in gridfs
+        at any time. Care must be taken to close GridFile instances when done
+        using them.
 
         Raises TypeError if file_spec is not an instance of dict, database is
         not an instance of `pymongo.database.Database`, or collection is not an