diff -r b428b803f71f Lib/ntpath.py
--- a/Lib/ntpath.py	Tue Apr 22 21:54:10 2014 -0400
+++ b/Lib/ntpath.py	Thu Apr 24 02:36:14 2014 -0400
@@ -498,7 +498,7 @@
 
     rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
     if not rel_list:
-        return curdir
+        return curdir if isinstance(path, str) else curdir.decode()
     return join(*rel_list)
 
 try:
diff -r b428b803f71f Lib/posixpath.py
--- a/Lib/posixpath.py	Tue Apr 22 21:54:10 2014 -0400
+++ b/Lib/posixpath.py	Thu Apr 24 02:36:14 2014 -0400
@@ -442,5 +442,5 @@
 
     rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
     if not rel_list:
-        return curdir
+        return curdir if isinstance(path, str) else curdir.decode()
     return join(*rel_list)
diff -r b428b803f71f Lib/test/test_ntpath.py
--- a/Lib/test/test_ntpath.py	Tue Apr 22 21:54:10 2014 -0400
+++ b/Lib/test/test_ntpath.py	Thu Apr 24 02:36:14 2014 -0400
@@ -250,6 +250,10 @@
         tester('ntpath.relpath("/a/b", "/a/b")', '.')
         tester('ntpath.relpath("c:/foo", "C:/FOO")', '.')
 
+    def test_relpath_return_type_consistent_with_input(self):
+        self.assertTrue(isinstance(os.path.relpath('.', '..'), str))
+        self.assertTrue(isinstance(os.path.relpath(u'.', u'..'), unicode))
+        self.assertTrue(isinstance(os.path.relpath(u'.', u'.'), unicode))
 
 class NtCommonTest(test_genericpath.CommonTest):
     pathmodule = ntpath
diff -r b428b803f71f Lib/test/test_posixpath.py
--- a/Lib/test/test_posixpath.py	Tue Apr 22 21:54:10 2014 -0400
+++ b/Lib/test/test_posixpath.py	Thu Apr 24 02:36:14 2014 -0400
@@ -409,6 +409,11 @@
         finally:
             os.getcwd = real_getcwd
 
+    def test_relpath_return_type_consistent_with_input(self):
+        self.assertTrue(isinstance(posixpath.relpath('.', '..'), str))
+        self.assertTrue(isinstance(posixpath.relpath(u'.', u'..'), unicode))
+        self.assertTrue(isinstance(posixpath.relpath(u'.', u'.'), unicode))
+
 
 class PosixCommonTest(test_genericpath.CommonTest):
     pathmodule = posixpath