diff --git a/hgext/uncommit.py b/hgext/uncommit.py
--- a/hgext/uncommit.py
+++ b/hgext/uncommit.py
@@ -45,6 +45,10 @@
     default=False,
 )
 
+configitem('experimental', 'uncommit.keep',
+    default=False,
+)
+
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
 # be specifying the version(s) of Mercurial they are tested with, or
@@ -136,7 +140,7 @@
         ds.copy(src, dst)
 
 @command('uncommit',
-    [('', 'keep', False, _('allow an empty commit after uncommiting')),
+    [('', 'keep', None, _('allow an empty commit after uncommiting')),
     ] + commands.walkopts,
     _('[OPTION]... [FILE]...'),
     helpcategory=command.CATEGORY_CHANGE_MANAGEMENT)
@@ -165,7 +169,12 @@
 
         with repo.transaction('uncommit'):
             match = scmutil.match(old, pats, opts)
-            keepcommit = opts.get('keep') or pats
+            keepcommit = pats
+            if not keepcommit:
+                if opts.get('keep') is not None:
+                    keepcommit = opts.get('keep')
+                else:
+                    keepcommit = ui.configbool('experimental', 'uncommit.keep')
             newid = _commitfiltered(repo, old, match, keepcommit)
             if newid is None:
                 ui.status(_("nothing to uncommit\n"))
diff --git a/tests/test-uncommit.t b/tests/test-uncommit.t
--- a/tests/test-uncommit.t
+++ b/tests/test-uncommit.t
@@ -307,7 +307,7 @@
   $ hg phase -r ".^"
   12: public
 
-Uncommit leaving an empty changeset
+Uncommit with --keep or experimental.uncommit.keep leaves an empty changeset
 
   $ cd $TESTTMP
   $ hg init repo1
@@ -327,9 +327,31 @@
   |/
   o  P FILES: P
   
+  $ cat >> .hg/hgrc <<EOF
+  > [experimental]
+  > uncommit.keep=True
+  > EOF
+  $ hg ci --amend
+  $ hg uncommit
+  note: keeping empty commit
+  $ hg log -G -T '{desc} FILES: {files}'
+  @  Q FILES:
+  |
+  | x  Q FILES: Q
+  |/
+  o  P FILES: P
+  
   $ hg status
   A Q
-
+  $ hg ci --amend
+  $ hg uncommit --no-keep
+  $ hg log -G -T '{desc} FILES: {files}'
+  x  Q FILES: Q
+  |
+  @  P FILES: P
+  
+  $ hg status
+  A Q
   $ cd ..
   $ rm -rf repo1