diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1787,10 +1787,16 @@ def import_(ui, repo, patch1, *patches, 
                     diffs_seen += 1
                     hgpatch = False
                     fp = cStringIO.StringIO()
+                    if message:
+                        fp.write(message)
+                        fp.write('\n')
                     for line in payload[:m.start(0)].splitlines():
                         if line.startswith('# HG changeset patch'):
                             ui.debug(_('patch generated by hg export\n'))
                             hgpatch = True
+                            # drop earlier commit message content
+                            fp.seek(0)
+                            fp.truncate()
                         elif hgpatch:
                             if line.startswith('# User '):
                                 user = line[7:]
@@ -1800,8 +1806,7 @@ def import_(ui, repo, patch1, *patches, 
                         if not line.startswith('# '):
                             fp.write(line)
                             fp.write('\n')
-                            hgpatch = False
-                    message = fp.getvalue() or message
+                    message = fp.getvalue()
                     if tmpfp:
                         tmpfp.write(payload)
                         if not payload.endswith('\n'):
diff --git a/tests/test-import b/tests/test-import
new file mode 100755
--- /dev/null
+++ b/tests/test-import
@@ -0,0 +1,81 @@
+#!/bin/sh
+
+hg init a
+echo line 1 > a/a
+hg --cwd a ci -d '0 0' -Ama
+
+echo line 2 >> a/a
+hg --cwd a ci -u someone -d '1 0' -m'second change'
+
+echo % import exported patch
+hg clone -r0 a b
+hg --cwd a export tip > tip.patch
+hg --cwd b import ../tip.patch
+echo % message should be same
+hg --cwd b tip | grep 'second change'
+echo % committer should be same
+hg --cwd b tip | grep someone
+rm -rf b
+
+echo % import of plain diff should fail without message
+hg clone -r0 a b
+hg --cwd a diff -r0:1 > tip.patch
+hg --cwd b import ../tip.patch
+rm -rf b
+
+echo % import of plain diff should be ok with message
+hg clone -r0 a b
+hg --cwd a diff -r0:1 > tip.patch
+hg --cwd b import -mpatch ../tip.patch
+rm -rf b
+
+echo % import from stdin
+hg clone -r0 a b
+hg --cwd a export tip | hg --cwd b import -
+rm -rf b
+
+echo % override commit message
+hg clone -r0 a b
+hg --cwd a export tip | hg --cwd b import -m 'override' -
+hg --cwd b tip | grep override
+rm -rf b
+
+cat > mkmsg.py <<EOF
+import email.Message, sys
+msg = email.Message.Message()
+msg.set_payload('email commit message\n' + open('tip.patch').read())
+msg['Subject'] = 'email patch'
+msg['From'] = 'email patcher'
+sys.stdout.write(msg.as_string())
+EOF
+
+echo % plain diff in email, subject, message body
+hg clone -r0 a b
+hg --cwd a diff -r0:1 > tip.patch
+python mkmsg.py > msg.patch
+hg --cwd b import ../msg.patch
+hg --cwd b tip | grep email
+rm -rf b
+
+echo % plain diff in email, no subject, message body
+hg clone -r0 a b
+grep -v '^Subject:' msg.patch | hg --cwd b import -
+rm -rf b
+
+echo % plain diff in email, subject, no message body
+hg clone -r0 a b
+grep -v '^email ' msg.patch | hg --cwd b import -
+rm -rf b
+
+echo % plain diff in email, no subject, no message body, should fail
+hg clone -r0 a b
+grep -v '^\(Subject\|email\)' msg.patch | hg --cwd b import -
+rm -rf b
+
+echo % hg export in email, should use patch header
+hg clone -r0 a b
+hg --cwd a export tip > tip.patch
+python mkmsg.py | hg --cwd b import -
+hg --cwd b tip | grep second
+rm -rf b
+
diff --git a/tests/test-import.out b/tests/test-import.out
new file mode 100644
--- /dev/null
+++ b/tests/test-import.out
@@ -0,0 +1,103 @@
+adding a
+% import exported patch
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying ../tip.patch
+patching file a
+% message should be same
+summary:     second change
+% committer should be same
+user:        someone
+% import of plain diff should fail without message
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying ../tip.patch
+patching file a
+transaction abort!
+rollback completed
+% import of plain diff should be ok with message
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying ../tip.patch
+patching file a
+% import from stdin
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying patch from stdin
+patching file a
+% override commit message
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying patch from stdin
+patching file a
+summary:     override
+% plain diff in email, subject, message body
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying ../msg.patch
+patching file a
+user:        email patcher
+summary:     email patch
+% plain diff in email, no subject, message body
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying patch from stdin
+patching file a
+% plain diff in email, subject, no message body
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying patch from stdin
+patching file a
+% plain diff in email, no subject, no message body, should fail
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying patch from stdin
+patching file a
+transaction abort!
+rollback completed
+% hg export in email, should use patch header
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying patch from stdin
+patching file a
+summary:     second change