diff --git i/Lib/unittest/main.py w/Lib/unittest/main.py
index a25a2f8..2917079 100644
--- i/Lib/unittest/main.py
+++ w/Lib/unittest/main.py
@@ -164,7 +164,10 @@ class TestProgram(object):
                 # to support python -m unittest ...
                 self.module = None
         else:
-            self.testNames = (self.defaultTest,)
+            if isinstance(self.defaultTest, str):
+                self.testNames = (self.defaultTest,)
+            else:
+                self.testNames = tuple(self.defaultTest)
         self.createTests()
 
     def createTests(self):
diff --git i/Lib/unittest/test/test_program.py w/Lib/unittest/test/test_program.py
index 9794868..1ac1e8b 100644
--- i/Lib/unittest/test/test_program.py
+++ w/Lib/unittest/test/test_program.py
@@ -64,6 +64,41 @@ class Test_TestProgram(unittest.TestCase):
             return self.suiteClass(
                 [self.loadTestsFromTestCase(Test_TestProgram.FooBar)])
 
+        def loadTestsFromNames(self, names, module):
+            return self.suiteClass(
+                [self.loadTestsFromTestCase(Test_TestProgram.FooBar)])
+
+    def test_defaultTest_with_string(self):
+        class FakeRunner(object):
+            def run(self, test):
+                self.test = test
+                return True
+
+        old_argv = sys.argv
+        sys.argv = ['faketest']
+        runner = FakeRunner()
+        program = unittest.TestProgram(testRunner=runner, exit=False,
+                                       defaultTest='unittest.test',
+                                       testLoader=self.FooBarLoader())
+        sys.argv = old_argv
+        self.assertEquals(('unittest.test',), program.testNames)
+
+    def test_defaultTest_with_iterable(self):
+        class FakeRunner(object):
+            def run(self, test):
+                self.test = test
+                return True
+
+        old_argv = sys.argv
+        sys.argv = ['faketest']
+        runner = FakeRunner()
+        program = unittest.TestProgram(
+            testRunner=runner, exit=False,
+            defaultTest=['unittest.test', 'unittest.test2'],
+            testLoader=self.FooBarLoader())
+        sys.argv = old_argv
+        self.assertEquals(('unittest.test', 'unittest.test2'),
+                          program.testNames)
 
     def test_NonExit(self):
         program = unittest.main(exit=False,