diff -r 3c29d05c0710 Lib/rlcompleter.py
--- a/Lib/rlcompleter.py	Fri Sep 04 23:57:25 2015 +0200
+++ b/Lib/rlcompleter.py	Sun Sep 06 00:25:55 2015 +0300
@@ -145,8 +145,16 @@ class Completer:
             words.extend(get_class_members(thisobject.__class__))
         matches = []
         n = len(attr)
+        if attr == '':
+            noprefix = '_'
+        elif attr == '_':
+            noprefix = '__'
+        else:
+            noprefix = None
         for word in words:
-            if word[:n] == attr and hasattr(thisobject, word):
+            if (word[:n] == attr and
+                not (noprefix and word[:n+1] == noprefix) and
+                hasattr(thisobject, word)):
                 val = getattr(thisobject, word)
                 word = self._callable_postfix(val, "%s.%s" % (expr, word))
                 matches.append(word)
diff -r 3c29d05c0710 Lib/test/test_rlcompleter.py
--- a/Lib/test/test_rlcompleter.py	Fri Sep 04 23:57:25 2015 +0200
+++ b/Lib/test/test_rlcompleter.py	Sun Sep 06 00:25:55 2015 +0300
@@ -5,6 +5,7 @@ import rlcompleter
 class CompleteMe:
     """ Trivial class used in testing rlcompleter.Completer. """
     spam = 1
+    _ham = 2
 
 
 class TestRlcompleter(unittest.TestCase):
@@ -56,6 +57,15 @@ class TestRlcompleter(unittest.TestCase)
         self.assertEqual(self.completer.attr_matches('CompleteMe.sp'),
                          ['CompleteMe.spam'])
         self.assertEqual(self.completer.attr_matches('Completeme.egg'), [])
+        self.assertEqual(self.completer.attr_matches('CompleteMe.'),
+                         ['CompleteMe.spam', 'CompleteMe.mro('])
+        self.assertEqual(self.completer.attr_matches('CompleteMe._'),
+                         ['CompleteMe._ham'])
+        a = self.completer.attr_matches('CompleteMe.__')
+        for x in a:
+            self.assertTrue(x.startswith('CompleteMe.__'), x)
+        self.assertIn('CompleteMe.__name__', a)
+        self.assertIn('CompleteMe.__new__(', a)
 
         CompleteMe.me = CompleteMe
         self.assertEqual(self.completer.attr_matches('CompleteMe.me.me.sp'),