diff -r b392a39970bb Lib/test/test_builtin.py
--- a/Lib/test/test_builtin.py	Sun Sep 30 22:48:20 2012 +0300
+++ b/Lib/test/test_builtin.py	Tue Oct 02 19:30:51 2012 +0200
@@ -1337,6 +1337,13 @@
             return {'a':2}
         __dict__ = property(fget=getDict)
 
+    class C_vars_slots(object):
+        __slots__ = 'x', 'y'
+        z = 1
+
+    class C_vars_dictslots(object):
+        __slots__ = '__dict__', 'foo'
+
     def test_vars(self):
         self.assertEqual(set(vars()), set(dir()))
         self.assertEqual(set(vars(sys)), set(dir(sys)))
@@ -1346,6 +1353,22 @@
         self.assertRaises(TypeError, vars, 42)
         self.assertEqual(vars(self.C_get_vars()), {'a':2})
 
+        # when no attribute is defined, should return a empty dict()
+        slot_test = self.C_vars_slots()
+        slot_test.x = 1
+        self.assertEqual(vars(self.C_vars_slots()), {})
+        self.assertEqual(vars(slot_test), {'x': 1})
+        # any new attribute shall be present
+        slot_test.y = 2
+        self.assertEqual(vars(slot_test), {'x': 1, 'y':2})
+        # having both __dict__ and __slots__, prevales __dict__
+        slot_test = self.C_vars_dictslots()
+        slot_test.cheese = 'spam'
+        self.assertEqual(vars(slot_test), {'cheese': 'spam'})
+        slot_test = type('slot_test', (self.C_vars_slots, ), {'a': 1, 'b': 2})
+        self.assertIn('a', set(vars(slot_test)))
+        self.assertIn('b', set(vars(slot_test)))
+
     def test_zip(self):
         a = (1, 2, 3)
         b = (4, 5, 6)
diff -r b392a39970bb Python/bltinmodule.c
--- a/Python/bltinmodule.c	Sun Sep 30 22:48:20 2012 +0300
+++ b/Python/bltinmodule.c	Tue Oct 02 19:30:51 2012 +0200
@@ -1899,6 +1899,8 @@
 {
     PyObject *v = NULL;
     PyObject *d;
+    _Py_IDENTIFIER(__dict__);
+    _Py_IDENTIFIER(__slots__);
 
     if (!PyArg_UnpackTuple(args, "vars", 0, 1, &v))
         return NULL;
@@ -1908,19 +1910,47 @@
             if (!PyErr_Occurred())
                 PyErr_SetString(PyExc_SystemError,
                                 "vars(): no locals!?");
-        }
-        else
+        } else
             Py_INCREF(d);
-    }
-    else {
-        _Py_IDENTIFIER(__dict__);
+    } else {
         d = _PyObject_GetAttrId(v, &PyId___dict__);
+        /* if no __dict__ attribute is found, try fetching __slots__ */
         if (d == NULL) {
-            PyErr_SetString(PyExc_TypeError,
-                "vars() argument must have __dict__ attribute");
-            return NULL;
+            PyObject *slots = _PyObject_GetAttrId(v, &PyId___slots__);
+            PyObject *iter, *item, *value;
+
+            if (slots == NULL) {
+                PyErr_SetString(PyExc_TypeError,
+                                "vars() argument must have __dict__ or\
+                                __slots__ attribute");
+                return NULL;
+            } else
+                PyErr_Clear();
+
+            iter = PyObject_GetIter(slots);
+            if (iter == NULL)
+                return NULL;
+
+            d = PyDict_New();
+            if (d == NULL)
+                return NULL;
+
+            while ((item = PyIter_Next(iter))) {
+                value = PyObject_GetAttr(v, item);
+                if (value == NULL)
+                    PyErr_Clear();
+                else if (PyDict_SetItem(d, item, value) != 0) {
+                    Py_DECREF(d);
+                    break;
+                }
+                Py_DECREF(item);
+                Py_XDECREF(value);
+            }
+            Py_DECREF(iter);
+            Py_DECREF(slots);
         }
     }
+
     return d;
 }
 
@@ -1928,7 +1958,10 @@
 "vars([object]) -> dictionary\n\
 \n\
 Without arguments, equivalent to locals().\n\
-With an argument, equivalent to object.__dict__.");
+With an argument, equivalent to object.__dict__\
+if present, object.__slots__ otherwise.\n\
+In case neither of the two is present raises\
+TypeError.\n");
 
 static PyObject*
 builtin_sum(PyObject *self, PyObject *args)