diff -r 0d230ad6b51a Doc/library/dbm.rst
--- a/Doc/library/dbm.rst	Tue Mar 11 14:26:21 2014 -0500
+++ b/Doc/library/dbm.rst	Tue Mar 11 22:57:45 2014 +0200
@@ -316,13 +316,17 @@
    dumbdbm database is created, files with :file:`.dat` and :file:`.dir` extensions
    are created.
 
-   The optional *flag* argument is currently ignored; the database is always opened
+   The optional *flag* argument is currently ignored, unless the value
+   is ``'n'``; otherwise, the database is always opened
    for update, and will be created if it does not exist.
 
    The optional *mode* argument is the Unix mode of the file, used only when the
    database has to be created.  It defaults to octal ``0o666`` (and will be modified
    by the prevailing umask).
 
+   .. versionchanged:: 3.5
+       :func:`.open` always creates a new database when the flag has the value ``'n'``.
+
    In addition to the methods provided by the
    :class:`collections.abc.MutableMapping` class, :class:`dumbdbm` objects
    provide the following method:
diff -r 0d230ad6b51a Lib/dbm/dumb.py
--- a/Lib/dbm/dumb.py	Tue Mar 11 14:26:21 2014 -0500
+++ b/Lib/dbm/dumb.py	Tue Mar 11 22:57:45 2014 +0200
@@ -44,7 +44,7 @@
     _os = _os       # for _commit()
     _io = _io       # for _commit()
 
-    def __init__(self, filebasename, mode):
+    def __init__(self, filebasename, mode, flag=None):
         self._mode = mode
 
         # The directory file is a text file.  Each line looks like
@@ -64,6 +64,17 @@
         # The index is an in-memory dict, mirroring the directory file.
         self._index = None  # maps keys to (pos, siz) pairs
 
+        # Handle the creation
+        self._create(flag)
+        self._update()
+
+    def _create(self, flag):
+        if flag == 'n':
+            for filename in (self._datfile, self._bakfile, self._dirfile):
+                try:
+                    _os.remove(filename)
+                except OSError:
+                    pass
         # Mod by Jack: create data file if needed
         try:
             f = _io.open(self._datfile, 'r', encoding="Latin-1")
@@ -71,7 +82,7 @@
             f = _io.open(self._datfile, 'w', encoding="Latin-1")
             self._chmod(self._datfile)
         f.close()
-        self._update()
+
 
     # Read directory file into the in-memory index dict.
     def _update(self):
@@ -247,16 +258,17 @@
     """Open the database file, filename, and return corresponding object.
 
     The flag argument, used to control how the database is opened in the
-    other DBM implementations, is ignored in the dbm.dumb module; the
-    database is always opened for update, and will be created if it does
-    not exist.
+    other DBM implementations, is ignored in the dbm.dumb module, unless
+    its value is "n", in which case the database will be a new, empty
+    database; otherwise database is always opened for update, and will be
+    created if it does not exist.
 
     The optional mode argument is the UNIX mode of the file, used only when
     the database has to be created.  It defaults to octal code 0o666 (and
     will be modified by the prevailing umask).
 
     """
-    # flag argument is currently ignored
+    # flag argument is currently ignored, except for "n"
 
     # Modify mode depending on the umask
     try:
@@ -268,4 +280,4 @@
         # Turn off any bits that are set in the umask
         mode = mode & (~um)
 
-    return _Database(file, mode)
+    return _Database(file, mode, flag=flag)
diff -r 0d230ad6b51a Lib/test/test_dbm_dumb.py
--- a/Lib/test/test_dbm_dumb.py	Tue Mar 11 14:26:21 2014 -0500
+++ b/Lib/test/test_dbm_dumb.py	Tue Mar 11 22:57:45 2014 +0200
@@ -196,6 +196,14 @@
         with self.assertRaises(Exception):
             db.keys()
 
+    def test_create_new(self):
+        with dumbdbm.open(_fname, 'n') as f:
+            for k in self._dict:
+                f[k] = self._dict[k]
+
+        with dumbdbm.open(_fname, 'n') as f:
+            self.assertEqual(f.keys(), [])
+
     def tearDown(self):
         _delete_files()