diff --git a/CHANGES b/CHANGES
index 5e8c57ca0..a44f322a9 100644
--- a/CHANGES
+++ b/CHANGES
@@ -31,6 +31,9 @@ Version 7.0
   See #790.
 - Allow autocompletion function to determine whether or not to return
   completions that start with the incomplete argument.
+- Subcommands that are named by the function now automatically have the
+  underscore replaced with a dash.  So if you register a function named
+  `my_command` it becomes `my-command` in the command line interface.
 
 Version 6.8
 -----------
diff --git a/click/decorators.py b/click/decorators.py
index c0b9e85a3..8e5a4627f 100644
--- a/click/decorators.py
+++ b/click/decorators.py
@@ -85,7 +85,7 @@ def _make_command(f, name, attrs, cls):
         help = inspect.cleandoc(help)
     attrs['help'] = help
     _check_for_unicode_literals()
-    return cls(name=name or f.__name__.lower(),
+    return cls(name=name or f.__name__.lower().replace('_', '-'),
                callback=f, params=params, **attrs)
 
 
@@ -105,7 +105,7 @@ def command(name=None, cls=None, **attrs):
     command :class:`Group`.
 
     :param name: the name of the command.  This defaults to the function
-                 name.
+                 name with underscores replaced by dashes.
     :param cls: the command class to instantiate.  This defaults to
                 :class:`Command`.
     """
diff --git a/tests/test_commands.py b/tests/test_commands.py
index 9b6a6fbca..e900c431f 100644
--- a/tests/test_commands.py
+++ b/tests/test_commands.py
@@ -62,7 +62,7 @@ def long():
         r'Commands:\n\s+'
         r'long\s+This is a long text that is too long to show\.\.\.\n\s+'
         r'short\s+This is a short text\.\n\s+'
-        r'special_chars\s+Login and store the token in ~/.netrc\.\s*',
+        r'special-chars\s+Login and store the token in ~/.netrc\.\s*',
         result.output) is not None
 
 
@@ -206,7 +206,7 @@ def cli(ctx):
     @click.option('--foo', type=click.INT, default=42)
     @click.pass_context
     def other_cmd(ctx, foo):
-        assert ctx.info_name == 'other_cmd'
+        assert ctx.info_name == 'other-cmd'
         click.echo(foo)
 
     result = runner.invoke(cli, [])
@@ -253,3 +253,17 @@ def cli(verbose, args):
         'Verbosity: 4',
         'Args: -foo|-x|--muhaha|x|y|-x',
     ]
+
+
+def test_subcommand_naming(runner):
+    @click.group()
+    def cli():
+        pass
+
+    @cli.command()
+    def foo_bar():
+        click.echo('foo-bar')
+
+    result = runner.invoke(cli, ['foo-bar'])
+    assert not result.exception
+    assert result.output.splitlines() == ['foo-bar']
diff --git a/tests/test_formatting.py b/tests/test_formatting.py
index 4c1c49131..b3de27775 100644
--- a/tests/test_formatting.py
+++ b/tests/test_formatting.py
@@ -74,11 +74,11 @@ def command():
 
     # 54 is chosen as a length where the second line is one character
     # longer than the maximum length.
-    result = runner.invoke(cli, ['a_very_long', 'command', '--help'],
+    result = runner.invoke(cli, ['a-very-long', 'command', '--help'],
                            terminal_width=54)
     assert not result.exception
     assert result.output.splitlines() == [
-        'Usage: cli a_very_long command [OPTIONS] FIRST SECOND',
+        'Usage: cli a-very-long command [OPTIONS] FIRST SECOND',
         '                               THIRD FOURTH FIFTH',
         '                               SIXTH',
         '',
@@ -111,11 +111,11 @@ def command():
         """A command.
         """
 
-    result = runner.invoke(cli, ['a_very_very_very_long', 'command', '--help'],
+    result = runner.invoke(cli, ['a-very-very-very-long', 'command', '--help'],
                            terminal_width=54)
     assert not result.exception
     assert result.output.splitlines() == [
-        'Usage: cli a_very_very_very_long command ',
+        'Usage: cli a-very-very-very-long command ',
         '           [OPTIONS] FIRST SECOND THIRD FOURTH FIFTH',
         '           SIXTH',
         '',