diff --git a/doc/hgrc.5.txt b/doc/hgrc.5.txt
--- a/doc/hgrc.5.txt
+++ b/doc/hgrc.5.txt
@@ -911,9 +911,6 @@ User interface controls.
     The conflict resolution program to use during a manual merge.
     For more information on merge tools see :hg:`help merge-tools`.
     For configuring merge tools see the merge-tools_ section.
-``patch``
-    command to use to apply patches. Look for ``gpatch`` or ``patch`` in
-    PATH if unset.
 ``quiet``
     Reduce the amount of output printed. True or False. Default is False.
 ``remotecmd``
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1559,45 +1559,6 @@ def debuginstall(ui):
         ui.write(_(" (templates seem to have been installed incorrectly)\n"))
         problems += 1
 
-    # patch
-    ui.status(_("Checking patch...\n"))
-    patchproblems = 0
-    a = "1\n2\n3\n4\n"
-    b = "1\n2\n3\ninsert\n4\n"
-    fa = writetemp(a)
-    d = mdiff.unidiff(a, None, b, None, os.path.basename(fa),
-        os.path.basename(fa))
-    fd = writetemp(d)
-
-    files = {}
-    try:
-        patch.patch(fd, ui, cwd=os.path.dirname(fa), files=files)
-    except util.Abort, e:
-        ui.write(_(" patch call failed:\n"))
-        ui.write(" " + str(e) + "\n")
-        patchproblems += 1
-    else:
-        if list(files) != [os.path.basename(fa)]:
-            ui.write(_(" unexpected patch output!\n"))
-            patchproblems += 1
-        a = open(fa).read()
-        if a != b:
-            ui.write(_(" patch test failed!\n"))
-            patchproblems += 1
-
-    if patchproblems:
-        if ui.config('ui', 'patch'):
-            ui.write(_(" (Current patch tool may be incompatible with patch,"
-                       " or misconfigured. Please check your configuration"
-                       " file)\n"))
-        else:
-            ui.write(_(" Internal patcher failure, please report this error"
-                       " to http://mercurial.selenic.com/wiki/BugTracker\n"))
-    problems += patchproblems
-
-    os.unlink(fa)
-    os.unlink(fd)
-
     # editor
     ui.status(_("Checking commit editor...\n"))
     editor = ui.geteditor()
diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -1156,7 +1156,7 @@ def _applydiff(ui, fp, patcher, copyfn, 
         return -1
     return err
 
-def externalpatch(patcher, patchname, ui, strip, cwd, files):
+def _externalpatch(patcher, patchname, ui, strip, cwd, files):
     """use <patcher> to apply <patchname> to the working directory.
     returns whether patch was applied with fuzz factor."""
 
@@ -1240,7 +1240,7 @@ def patch(patchname, ui, strip=1, cwd=No
         files = {}
     try:
         if patcher:
-            return externalpatch(patcher, patchname, ui, strip, cwd, files)
+            return _externalpatch(patcher, patchname, ui, strip, cwd, files)
         return internalpatch(patchname, ui, strip, cwd, files, eolmode)
     except PatchError, err:
         raise util.Abort(str(err))
diff --git a/tests/test-install.t b/tests/test-install.t
--- a/tests/test-install.t
+++ b/tests/test-install.t
@@ -3,7 +3,6 @@ hg debuginstall
   Checking encoding (ascii)...
   Checking installed modules (*/mercurial)... (glob)
   Checking templates...
-  Checking patch...
   Checking commit editor...
   Checking username...
   No problems detected
@@ -13,7 +12,6 @@ hg debuginstall with no username
   Checking encoding (ascii)...
   Checking installed modules (*/mercurial)... (glob)
   Checking templates...
-  Checking patch...
   Checking commit editor...
   Checking username...
    no username supplied (see "hg help config")