diff --git a/hgext3rd/undo.py b/hgext3rd/undo.py
--- a/hgext3rd/undo.py
+++ b/hgext3rd/undo.py
@@ -206,7 +206,7 @@
     revstring = "\n".join(sorted('%s %s' % (k, v) for k, v in nodes.items()))
     return writelog(repo, tr, "index.i", revstring)
 
-def _logundoredoindex(repo, tr, reverseindex, branch=""):
+def _logundoredoindex(repo, reverseindex, branch=""):
     rlog = _getrevlog(repo, 'index.i')
     hexnode = hex(rlog.node(_invertindex(rlog, reverseindex)))
     return repo.vfs.write("undolog/redonode", str(hexnode) + "\0" + branch)
@@ -566,18 +566,19 @@
 
     if branch and reverseindex != 1:
         raise error.Abort(_("--branch with --index not supported"))
+    if relativeundo:
+        reverseindex = _computerelative(repo, reverseindex,
+                                        absolute = not relativeundo,
+                                        branch = branch)
 
     if preview:
-        _preview(ui, repo)
+        _preview(ui, repo, reverseindex)
         return
 
     with repo.wlock(), repo.lock(), repo.transaction("undo"):
         cmdutil.checkunfinished(repo)
         cmdutil.bailifchanged(repo)
         repo = repo.unfiltered()
-        reverseindex = _computerelative(repo, reverseindex,
-                                        absolute=not relativeundo,
-                                        branch=branch)
         if not (opts.get("force") or _gapcheck(repo, reverseindex)):
             raise error.Abort(_("attempted risky undo across"
                                 " missing history"))
@@ -586,12 +587,14 @@
         # store undo data
         # for absolute undos, think of this as a reset
         # for relative undos, think of this as an update
-        _logundoredoindex(repo, repo.currenttransaction(), reverseindex, branch)
+        _logundoredoindex(repo, reverseindex, branch)
 
 @command('redo', [
     ('b', 'branch', "", _("single branch undo, accepts commit hash "
                           "(ADVANCED)")),
     ('n', 'index', 1, _("how many commands to redo")),
+    ('p', 'preview', False, _("see smartlog like preview of future redo "
+                              "state")),
 ])
 def redo(ui, repo, *args, **opts):
     """ perform a redo
@@ -605,17 +608,23 @@
     """
     branch = opts.get("branch")
     reverseindex = -1 * abs(opts.get("index"))
+    preview = opts.get("preview")
 
     if branch and reverseindex != -1:
         raise error.Abort(_("--branch with --index not supported"))
 
+    reverseindex = _computerelative(repo, reverseindex)
+
+    if preview:
+        _preview(ui, repo, reverseindex)
+        return
+
     with repo.wlock(), repo.lock(), repo.transaction("redo"):
         cmdutil.checkunfinished(repo)
         cmdutil.bailifchanged(repo)
         repo = repo.unfiltered()
-        reverseindex = _computerelative(repo, reverseindex, branch=branch)
         _undoto(ui, repo, reverseindex, branch=branch)
-        _logundoredoindex(repo, repo.currenttransaction(), reverseindex, branch)
+        _logundoredoindex(repo, reverseindex, branch=branch)
 
 def _undoto(ui, repo, reverseindex, keep=False, branch=None):
     # undo to specific reverseindex
@@ -879,7 +888,7 @@
         ctxts = repo.set(rev)
         inhibit.revive(ctxts)
 
-def _preview(ui, repo):
+def _preview(ui, repo, reverseindex):
     # Print smartlog like preview of undo
     # Input:
     #   ui:
@@ -887,15 +896,23 @@
     # Output:
     #   None
 
-    reverseindex = 1
-    opts = {}
-    opts["template"] = "{undopreview}"
-    reverseindex = _computerelative(repo, reverseindex)
-    repo = repo.unfiltered()
-    revstring = revsetlang.formatspec("olddraft(%d) + olddraft(0)",
-                                      reverseindex)
-    opts['rev'] = [revstring]
-    cmdutil.graphlog(ui, repo, None, opts)
+    savedindex = _computerelative(repo, 0)
+    _logundoredoindex(repo, reverseindex - 1)
+    try:
+        opts = {}
+        opts["template"] = "{undopreview}"
+        repo = repo.unfiltered()
+        revstring = revsetlang.formatspec("olddraft(%d) + olddraft(0)",
+                                          reverseindex)
+        opts['rev'] = [revstring]
+        try:
+            cmdutil.graphlog(ui, repo, None, opts)
+        except IndexError:
+            # don't print anything
+            pass
+    finally: # always restore undoredo
+        _logundoredoindex(repo, savedindex)
+    return
 
 # Tools
 
diff --git a/tests/test-undo.t b/tests/test-undo.t
--- a/tests/test-undo.t
+++ b/tests/test-undo.t
@@ -709,6 +709,8 @@
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > smartlog = $TESTDIR/../hgext3rd/smartlog.py
+  > [templatealias]
+  > undopreview = '{if(undonecommits, "Undone")}'
   > EOF
   $ touch prev1 && hg add prev1 && hg ci -m prev1
   $ hg log -Gr "olddraft(1) + olddraft(0)" -T "{label(sl_label, separate('\n', separate('  ', separate(' ', label('sl.oldbook', '{if(undonecommits, shortest(undonecommits, 6))}'), label('sl.book', '{label('sl.book', '{if(donecommits, shortest(donecommits, 6))}')}')), sl_user, sl_diff, separate(' ', label('sl.book', oldbookmarks), label('sl.oldbook', removedbookmarks))), '{sl_desc}', '\n'))}"
@@ -731,6 +733,46 @@
   o  49cdb4  feature1
   |
   ~
+  $ hg undo -p
+  @  Undone
+  |
+  o
+  |
+  | o
+  |/
+  o
+  |
+  o
+  |
+  o
+  |
+  ~
+  o
+  |
+  ~
+  o
+  |
+  ~
+  $ hg undo -p -n 2
+  @  Undone
+  |
+  o  Undone
+  |
+  | o
+  |/
+  o
+  |
+  o
+  |
+  o
+  |
+  ~
+  o
+  |
+  ~
+  o
+  |
+  ~
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > smartlog =!