diff --git a/Lib/http/cookies.py b/Lib/http/cookies.py
--- a/Lib/http/cookies.py
+++ b/Lib/http/cookies.py
@@ -431,16 +431,18 @@ class Morsel(dict):
             if value == "":
                 continue
             if key not in attrs:
                 continue
             if key == "expires" and isinstance(value, int):
                 append("%s=%s" % (self._reserved[key], _getdate(value)))
             elif key == "max-age" and isinstance(value, int):
                 append("%s=%d" % (self._reserved[key], value))
+            elif key == "comment" and isinstance(value, str):
+                append("%s=%s" % (self._reserved[key], _quote(value)))
             elif key in self._flags:
                 if value:
                     append(str(self._reserved[key]))
             else:
                 append("%s=%s" % (self._reserved[key], value))
 
         # Return the result
         return _semispacejoin(result)
diff --git a/Lib/test/test_http_cookies.py b/Lib/test/test_http_cookies.py
--- a/Lib/test/test_http_cookies.py
+++ b/Lib/test/test_http_cookies.py
@@ -211,16 +211,26 @@ class CookieTests(unittest.TestCase):
                 self.assertEqual(C1.output(), expected_output)
 
     def test_illegal_chars(self):
         rawdata = "a=b; c,d=e"
         C = cookies.SimpleCookie()
         with self.assertRaises(cookies.CookieError):
             C.load(rawdata)
 
+    def test_comment_quoting(self):
+        c = cookies.SimpleCookie()
+        c['foo'] = '\N{COPYRIGHT SIGN}'
+        self.assertEqual(str(c['foo']), 'Set-Cookie: foo="\\251"')
+        c['foo']['comment'] = 'comment \N{COPYRIGHT SIGN}'
+        self.assertEqual(
+            str(c['foo']),
+            'Set-Cookie: foo="\\251"; Comment="comment \\251"'
+        )
+
 
 class MorselTests(unittest.TestCase):
     """Tests for the Morsel object."""
 
     def test_defaults(self):
         morsel = cookies.Morsel()
         self.assertIsNone(morsel.key)
         self.assertIsNone(morsel.value)