diff -r d7dede0eabd8 Lib/test/test_urllib2.py
--- a/Lib/test/test_urllib2.py	Tue Mar 19 12:18:50 2013 -0700
+++ b/Lib/test/test_urllib2.py	Tue Mar 19 13:20:52 2013 -0700
@@ -1443,6 +1443,12 @@
         self.assertEqual(b"1234567890", request.data)
         self.assertEqual("10", request.get_header("Content-length"))
 
+        del request.data
+        opener.open(request)
+
+        self.assertEqual(None, request.data)
+        self.assertEqual(None, request.get_header("Content-length"))
+
     def test_HTTPError_interface(self):
         """
         Issue 13211 reveals that HTTPError didn't implement the URLError
diff -r d7dede0eabd8 Lib/urllib/request.py
--- a/Lib/urllib/request.py	Tue Mar 19 12:18:50 2013 -0700
+++ b/Lib/urllib/request.py	Tue Mar 19 13:20:52 2013 -0700
@@ -296,7 +296,7 @@
 
     @data.deleter
     def data(self):
-        self._data = None
+        self.data = None
 
     def _parse(self):
         self.type, rest = splittype(self.full_url)