diff --git a/hgext3rd/undo.py b/hgext3rd/undo.py
--- a/hgext3rd/undo.py
+++ b/hgext3rd/undo.py
@@ -539,8 +539,11 @@
     keep = opts.get("keep")
     preview = opts.get("preview")
 
+    if relativeundo:
+        reverseindex = _computerelative(repo, reverseindex)
+
     if preview:
-        _undopreview(ui, repo, **opts)
+        _undopreview(ui, repo, reverseindex, **opts)
         return
 
     with repo.wlock(), repo.lock(), repo.transaction("undo"):
@@ -560,6 +563,8 @@
 
 @command('redo', [
     ('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
@@ -573,6 +578,11 @@
     """
     reverseindex = -1 * abs(opts.get("index"))
     reverseindex = _computerelative(repo, reverseindex)
+    preview = opts.get("preview")
+
+    if preview:
+        _undopreview(ui, repo, reverseindex, **opts)
+        return
 
     with repo.wlock(), repo.lock(), repo.transaction("redo"):
         cmdutil.checkunfinished(repo)
@@ -706,7 +716,7 @@
         ctxts = repo.set(rev)
         inhibit.revive(ctxts)
 
-def _undopreview(ui, repo, **opts):
+def _undopreview(ui, repo, reverseindex, **opts):
     # Print smartlog like preview of undo
     # Input:
     #   ui:
@@ -715,13 +725,15 @@
     # Output:
     #   None
     # Requires smartlog extension
+    savedindex = _computerelative(repo, 0)
     try:
         smartlog = extensions.find('smartlog')
     except KeyError:
         raise error.Abort(_('undo requires smartlog to work properly'))
-    reverseindex = opts.get("index")
+    # overwrite undoredo with fake index, so that relative calls of 1 will
+    # return the index we want
+    _logundoredoindex(repo, repo.currenttransaction(), reverseindex - 1)
     opts["template"] = "{undopreview}"
-    reverseindex = _computerelative(repo, reverseindex)
     revstring = revsetlang.formatspec("olddraft(%d)", reverseindex)
     revs = set()
     try:
@@ -744,6 +756,7 @@
         displayer = cmdutil.show_changeset(ui, repo, opts, buffered=True)
         cmdutil.displaygraph(
             ui, repo, revdag, displayer, graphmod.asciiedges, None, None)
+    _logundoredoindex(repo, repo.currenttransaction(), savedindex)
     return
 
 # Tools