diff --git a/pymongo/collection.py b/pymongo/collection.py
index cacf5f3dd..1c5ae0ce7 100644
--- a/pymongo/collection.py
+++ b/pymongo/collection.py
@@ -1270,10 +1270,12 @@ class Collection(common.BaseObject):
         client = self.database.connection
         client._ensure_connected(True)
 
+        slave_okay = not client._rs_client and not client.is_mongos
         if client.max_wire_version > 2:
             res, addr = self.__database._command(
                 "listIndexes", self.__name, as_class=SON,
-                cursor={}, read_preference=ReadPreference.PRIMARY)
+                cursor={}, slave_okay=slave_okay,
+                read_preference=ReadPreference.PRIMARY)
             # MongoDB 2.8rc2
             if "indexes" in res:
                 raw = res["indexes"]
@@ -1283,6 +1285,7 @@ class Collection(common.BaseObject):
         else:
             raw = self.__database.system.indexes.find({"ns": self.__full_name},
                                                       {"ns": 0}, as_class=SON,
+                                                      slave_okay=slave_okay,
                                                       _must_use_master=True)
         info = {}
         for index in raw:
@@ -1303,12 +1306,14 @@ class Collection(common.BaseObject):
         client._ensure_connected(True)
 
         result = None
+        slave_okay = not client._rs_client and not client.is_mongos
         if client.max_wire_version > 2:
             res, addr = self.__database._command(
                 "listCollections",
                 cursor={},
                 filter={"name": self.__name},
-                read_preference=ReadPreference.PRIMARY)
+                read_preference=ReadPreference.PRIMARY,
+                slave_okay=slave_okay)
             # MongoDB 2.8rc2
             if "collections" in res:
                 results = res["collections"]
@@ -1320,7 +1325,9 @@ class Collection(common.BaseObject):
                 break
         else:
             result = self.__database.system.namespaces.find_one(
-                {"name": self.__full_name}, _must_use_master=True)
+                {"name": self.__full_name},
+                slave_okay=slave_okay,
+                _must_use_master=True)
 
         if not result:
             return {}
diff --git a/pymongo/database.py b/pymongo/database.py
index f8ab8cb17..b42579425 100644
--- a/pymongo/database.py
+++ b/pymongo/database.py
@@ -448,10 +448,12 @@ class Database(common.BaseObject):
         client = self.connection
         client._ensure_connected(True)
 
+        slave_okay = not client._rs_client and not client.is_mongos
         if client.max_wire_version > 2:
             res, addr = self._command("listCollections",
                                       cursor={},
-                                      read_preference=ReadPreference.PRIMARY)
+                                      read_preference=ReadPreference.PRIMARY,
+                                      slave_okay=slave_okay)
             # MongoDB 2.8rc2
             if "collections" in res:
                 results = res["collections"]
@@ -461,7 +463,9 @@ class Database(common.BaseObject):
             names = [result["name"] for result in results]
         else:
             names = [result["name"] for result
-                     in self["system.namespaces"].find(_must_use_master=True)]
+                     in self["system.namespaces"].find(
+                         slave_okay=slave_okay,
+                         _must_use_master=True)]
             names = [n[len(self.__name) + 1:] for n in names
                      if n.startswith(self.__name + ".") and "$" not in n]
 
diff --git a/pymongo/mongo_client.py b/pymongo/mongo_client.py
index 3a41c5de3..b762a31aa 100644
--- a/pymongo/mongo_client.py
+++ b/pymongo/mongo_client.py
@@ -1373,9 +1373,14 @@ class MongoClient(common.BaseObject):
     def database_names(self):
         """Get a list of the names of all databases on the connected server.
         """
+        # SERVER-15994 changed listDatabases to require slaveOk when run
+        # against a secondary / slave. Passing slave_okay=True makes things
+        # consistent across server versions.
         return [db["name"] for db in
-                self.admin.command("listDatabases",
-                    read_preference=ReadPreference.PRIMARY)["databases"]]
+                self.admin.command(
+                    "listDatabases",
+                    read_preference=ReadPreference.PRIMARY,
+                    slave_okay=not self.is_mongos)["databases"]]
 
     def drop_database(self, name_or_database):
         """Drop a database.
diff --git a/test/test_read_preferences.py b/test/test_read_preferences.py
index bd0f30f3e..2bc9c811a 100644
--- a/test/test_read_preferences.py
+++ b/test/test_read_preferences.py
@@ -82,6 +82,24 @@ class TestReadPreferencesBase(TestReplicaSetClientBase):
             expected, used))
 
 
+class TestSlaveOkayMetadataCommands(TestReadPreferencesBase):
+
+    def test_slave_okay_metadata_commands(self):
+
+        secondaries = iter(self._get_client().secondaries)
+        host, port = secondaries.next()
+        # Direct connection to a secondary.
+        client = MongoClient(host, port)
+        self.assertFalse(client.is_primary)
+        self.assertEqual(client.read_preference, ReadPreference.PRIMARY)
+
+        # No error.
+        client.database_names()
+        client.pymongo_test.collection_names()
+        client.pymongo_test.test.options()
+        client.pymongo_test.test.index_information()
+
+
 class TestReadPreferences(TestReadPreferencesBase):
     def test_mode_validation(self):
         # 'modes' are imported from read_preferences.py