diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -13,6 +13,7 @@ import hg, scmutil, util, revlog, extens
 import patch, help, url, encoding, templatekw, discovery
 import archival, changegroup, cmdutil, hbisect
 import sshserver, hgweb, hgweb.server, commandserver
+import match as matchmod
 import merge as mergemod
 import minirst, revset, fileset
 import dagparser, context, simplemerge
@@ -2432,23 +2433,45 @@ def forget(ui, repo, *pats, **opts):
     if not pats:
         raise util.Abort(_('no files specified'))
 
-    m = scmutil.match(repo[None], pats, opts)
+    wctx = repo[None]
+    m = scmutil.match(wctx, pats, opts)
     s = repo.status(match=m, clean=True)
     forget = sorted(s[0] + s[1] + s[3] + s[6])
+    subforget = {}
     errs = 0
 
+    for subpath in wctx.substate:
+        sub = wctx.sub(subpath)
+        try:
+            submatch = matchmod.narrowmatcher(subpath, m)
+            for fsub in sub.walk(submatch):
+                if submatch.exact(fsub):
+                    subforget[os.path.join(subpath, fsub)] = (fsub, sub)
+        except error.LookupError:
+            ui.status(_("skipping missing subrepository: %s\n") % subpath)
+
     for f in m.files():
         if f not in repo.dirstate and not os.path.isdir(m.rel(f)):
-            if os.path.exists(m.rel(f)):
-                ui.warn(_('not removing %s: file is already untracked\n')
-                        % m.rel(f))
-            errs = 1
+            if f not in subforget:
+                if os.path.exists(m.rel(f)):
+                    ui.warn(_('not removing %s: file is already untracked\n')
+                            % m.rel(f))
+                errs = 1
 
     for f in forget:
         if ui.verbose or not m.exact(f):
             ui.status(_('removing %s\n') % m.rel(f))
 
-    repo[None].forget(forget)
+    if ui.verbose:
+        for f in sorted(subforget.keys()):
+            ui.status(_('removing %s\n') % m.rel(f))
+
+    wctx.forget(forget)
+
+    for f in sorted(subforget.keys()):
+        fsub, sub = subforget[f]
+        sub.forget([fsub])
+
     return errs
 
 @command(
diff --git a/mercurial/help/subrepos.txt b/mercurial/help/subrepos.txt
--- a/mercurial/help/subrepos.txt
+++ b/mercurial/help/subrepos.txt
@@ -95,6 +95,9 @@ Interaction with Mercurial Commands
     elements. Git and Subversion subrepositories are currently
     silently ignored.
 
+:forget: forget currently only handles exact file matches in subrepos.
+    Git and Subversion subrepositories are currently silently ignored.
+
 :incoming: incoming does not recurse in subrepos unless -S/--subrepos
     is specified. Git and Subversion subrepositories are currently
     silently ignored.
diff --git a/mercurial/subrepo.py b/mercurial/subrepo.py
--- a/mercurial/subrepo.py
+++ b/mercurial/subrepo.py
@@ -360,6 +360,9 @@ class abstractsubrepo(object):
         '''
         pass
 
+    def forget(self, files):
+        pass
+
 class hgsubrepo(abstractsubrepo):
     def __init__(self, ctx, path, state):
         self._path = path
@@ -553,6 +556,10 @@ class hgsubrepo(abstractsubrepo):
         ctx = self._repo[None]
         return ctx.walk(match)
 
+    def forget(self, files):
+        ctx = self._repo[None]
+        ctx.forget(files)
+
 class svnsubrepo(abstractsubrepo):
     def __init__(self, ctx, path, state):
         self._path = path
diff --git a/tests/test-subrepo.t b/tests/test-subrepo.t
--- a/tests/test-subrepo.t
+++ b/tests/test-subrepo.t
@@ -1006,12 +1006,12 @@ Adding with a pattern with -S also adds 
   committing subrepository s
 
 Test behavior of forget for explicit path in subrepo:
-Forgetting an explicit path in a subrepo currently gives a file untracked warn
+Forgetting an explicit path in a subrepo untracks the file
   $ echo c19 > s/f19
   $ hg add s/f19
   $ hg st -S
   A s/f19
   $ hg forget s/f19
-  not removing s/f19: file is already untracked
-  [1]
+  $ hg st -S
+  ? s/f19
   $ rm s/f19