diff --git a/plugins/mongodb/mongo_lag b/plugins/mongodb/mongo_lag
new file mode 100755
index 00000000..1f883721
--- /dev/null
+++ b/plugins/mongodb/mongo_lag
@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+"""
+    MongoDB Replication Lag
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    Connects to a single mongo instance and retrieve
+    replication lag for all connected members.
+
+    munin-node.conf:
+    [mongodb_lag]
+    env.host 127.0.0.1
+    env.port 27017
+
+    :author: Stefan Andersen <stefan@stefanandersen.dk>
+    :license: The Beer Ware License (Revision 42)
+              <stefan@stefanandersen.dk> wrote this file. As long 
+              as you retain this notice you can do whatever you want 
+              with this stuff. If we meet some day, and you think 
+              this stuff is worth it, you can buy me a beer in return. 
+"""
+import os
+import sys
+import pymongo
+
+def _get_members():
+    host = os.environ.get('host', '127.0.0.1')
+    port = os.environ.get('port', 27017)
+    conn = pymongo.Connection(host)
+    repl_status = conn.admin.command("replSetGetStatus")
+
+    members = {}
+    for member in repl_status['members']:
+        name = member['name'].split('.')[0]
+        members[name] = {'state': member['state'], 'optimeDate': member['optimeDate']}
+    return members
+
+def run():
+    members = _get_members();
+    for member in members:
+        if members[member]['state'] == 1:
+            primary_optime = members[member]['optimeDate']
+
+    for member in members:
+        members[member]['lag'] = (primary_optime - members[member]['optimeDate']).seconds
+
+    print "multigraph mongodb_replication_lag"
+    for member in members:
+        print "{}_lag.value {}".format(member, members[member]['lag'])
+    print
+
+    for member in members:
+        print "multigraph mongodb_replication_lag.{}".format(member)
+        print "lag.value {}".format(members[member]['lag'])
+        print
+
+def config():
+    print """graph_title MongoDB replication lag
+graph_args --base 1000
+graph_vlabel Replication lag (seconds)
+graph_category MongoDB
+"""
+
+    for member in _get_members():
+        print "{0}_lag.label {0}".format(member)
+        print "{}_lag.type GAUGE".format(member)
+        print "{}_lag.info Replication lag behind master".format(member)
+        print "{}_lag.min 0".format(member)
+        print "{}_lag.draw LINE1".format(member)
+        print 
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1 and sys.argv[1] == "config":
+        config()
+    else:
+        run()