diff --git a/prompt_toolkit/shortcuts/dialogs.py b/prompt_toolkit/shortcuts/dialogs.py
index fa8d0554d..742b7f4c7 100644
--- a/prompt_toolkit/shortcuts/dialogs.py
+++ b/prompt_toolkit/shortcuts/dialogs.py
@@ -111,14 +111,14 @@ def message_dialog(title='', text='', ok_text='Ok', style=None, async_=False):
 
 
 def radiolist_dialog(title='', text='', ok_text='Ok', cancel_text='Cancel',
-                     values=None, style=None, async_=False):
+                     values=None, style=None, async_=False, default=0):
     """
     Display a simple message box and wait until the user presses enter.
     """
     def ok_handler():
         get_app().exit(result=radio_list.current_value)
 
-    radio_list = RadioList(values)
+    radio_list = RadioList(values, default)
 
     dialog = Dialog(
         title=title,
diff --git a/prompt_toolkit/widgets/base.py b/prompt_toolkit/widgets/base.py
index a90709ba0..eeee7aeb5 100644
--- a/prompt_toolkit/widgets/base.py
+++ b/prompt_toolkit/widgets/base.py
@@ -497,16 +497,20 @@ class RadioList(object):
     List of radio buttons. Only one can be checked at the same time.
 
     :param values: List of (value, label) tuples.
+    :param default: Default index to select, defaults to 0
     """
-    def __init__(self, values):
+    def __init__(self, values, default=0):
         assert isinstance(values, list)
         assert len(values) > 0
         assert all(isinstance(i, tuple) and len(i) == 2
                    for i in values)
+        assert isinstance(default, int)
+        assert 0 <= default < len(values)
 
         self.values = values
-        self.current_value = values[0][0]
-        self._selected_index = 0
+
+        self.current_value = values[default][0]
+        self._selected_index = default
 
         # Key bindings.
         kb = KeyBindings()
diff --git a/tests/test_radiolist.py b/tests/test_radiolist.py
new file mode 100644
index 000000000..4b414ff4b
--- /dev/null
+++ b/tests/test_radiolist.py
@@ -0,0 +1,96 @@
+from __future__ import unicode_literals
+
+from prompt_toolkit.widgets import RadioList
+
+import pytest
+
+def test_initial():
+    values = [
+                (1, 'some_text'),
+                ('fizz', 'some_more_text'),
+                ({'foo':'bar'}, 'even_more_text')
+             ]
+    radiolist = RadioList(values)
+    assert radiolist.current_value == 1
+    assert radiolist._selected_index == 0
+
+def test_default():
+    values = [
+                (1, 'some_text'),
+                ('fizz', 'some_more_text'),
+                ({'foo':'bar'}, 'even_more_text')
+             ]
+    radiolist = RadioList(values, 1)
+    assert radiolist.current_value == 'fizz'
+    assert radiolist._selected_index == 1
+
+def test_bad_params():
+    with pytest.raises(AssertionError):
+        radiolist = RadioList([])
+
+    with pytest.raises(AssertionError):
+        radiolist = RadioList(None)
+
+    with pytest.raises(AssertionError):
+        values = (
+                    (1, 'some_text'),
+                    ('fizz', 'some_more_text'),
+                    ({'foo':'bar'}, 'even_more_text')
+                 )
+        radiolist = RadioList(values)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text', 'whoops'),
+                    ('fizz', 'some_more_text'),
+                    ({'foo':'bar'}, 'even_more_text')
+                 ]
+        radiolist = RadioList(values)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text'),
+                    ('fizz', ),
+                    ({'foo':'bar'}, 'even_more_text')
+                 ]
+        radiolist = RadioList(values)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text'),
+                    ('fizz', 'some_more_text'),
+                    [{'foo':'bar'}, 'even_more_text']
+                 ]
+        radiolist = RadioList(values)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text'),
+                    ('fizz', 'some_more_text'),
+                    ({'foo':'bar'}, 'even_more_text')
+                 ]
+        radiolist = RadioList(values, 3)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text'),
+                    ('fizz', 'some_more_text'),
+                    ({'foo':'bar'}, 'even_more_text')
+                 ]
+        radiolist = RadioList(values, -1)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text'),
+                    ('fizz', 'some_more_text'),
+                    ({'foo':'bar'}, 'even_more_text')
+                 ]
+        radiolist = RadioList(values, None)
+
+    with pytest.raises(AssertionError):
+        values = [
+                    (1, 'some_text'),
+                    ('fizz', 'some_more_text'),
+                    ({'foo':'bar'}, 'even_more_text')
+                 ]
+        radiolist = RadioList(values, 'whoops')