diff --git a/Lib/test/test_unittest.py b/Lib/test/test_unittest.py
index 459334b..de687e2 100644
--- a/Lib/test/test_unittest.py
+++ b/Lib/test/test_unittest.py
@@ -2500,6 +2500,18 @@
         self.assertIsNot(thing, object())
         self.assertRaises(self.failureException, self.assertIsNot, thing, thing)
 
+    def testAssertIsInstance(self):
+        thing = []
+        self.assertIsInstance(thing, list)
+        self.assertRaises(self.failureException, self.assertIsInstance,
+                          thing, dict)
+
+    def testAssertNotIsInstance(self):
+        thing = []
+        self.assertNotIsInstance(thing, dict)
+        self.assertRaises(self.failureException, self.assertNotIsInstance,
+                          thing, list)
+
     def testAssertIn(self):
         animals = {'monkey': 'banana', 'cow': 'grass', 'seal': 'fish'}
 
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index fb96a88..113422c 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -817,6 +817,19 @@
             standardMsg = 'unexpectedly None'
             self.fail(self._formatMessage(msg, standardMsg))
 
+    def assertIsInstance(self, obj, cls, msg=None):
+        """Same as self.assertTrue(isinstance(obj, cls)), with a nicer
+        default message."""
+        if not isinstance(obj, cls):
+            standardMsg = '%r is not an instance of %r' % (obj, cls)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertNotIsInstance(self, obj, cls, msg=None):
+        """Included for symmetry with assertIsInstance."""
+        if isinstance(obj, cls):
+            standardMsg = '%r is an instance of %r' % (obj, cls)
+            self.fail(self._formatMessage(msg, standardMsg))
+
     def assertRaisesRegexp(self, expected_exception, expected_regexp,
                            callable_obj=None, *args, **kwargs):
         """Asserts that the message in a raised exception matches a regexp.