 <ol> <li>Don't add the markers to the map, let the MarkerManager do that</li> <li>If you are only adding a single marker, use <code>.addMarker</code>, not <code>.addMarkers</code></li> </ol> <p><a href="http://jsfiddle.net/geocodezip/ee7nbaL1/1/" rel="nofollow">proof of concept fiddle</a></p> <p><strong>code snippet:</strong></p> <p><div class="snippet" data-lang="js" data-hide="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>var mgr; var map; function initialize() { var mapOptions = { zoom: 4, center: new google.maps.LatLng(34.6479355684, -0.2292535), mapTypeId: google.maps.MapTypeId.SATELLITE }; map = new google.maps.Map(document.getElementById('resultcnn'), mapOptions); mgr = new MarkerManager(map); var locations = [ ['rabat', 33.906896, -6.263123], ['rabat2', 34.053993, -6.792237], ['agdal', 33.994469, -6.848702], ['casa', 33.587596, -7.657156], ['casa2', 33.531808, -7.674601], ['casa3', 33.58824, -7.673278], ['casa4', 33.542325, -7.578557], ['agadir', 30.433948, -9.600005], ['kech', 31.634676, -8.000164], ['oujda,', 34.689969, -1.912365], ['tanger,', 35.771586, -5.801868], ['JIJEL-ACHOUAT', 36.8, 5.883333333, 1], ['JIJEL-PORT', 36.81666667, 5.883333333, 2], ['SKIKDA', 36.88333333, 6.9, 3], ['ANNABA', 36.83333333, 7.816666667, 4], ['EL-KALA', 36.9, 8.45, 8], ['ALGER-PORT', 36.76666667, 3.1, 9], ['DELLYS', 36.91666667, 3.95, 10.4], ['DAR-EL-BEIDA', 36.68333333, 3.216666667, 12.08571429], ['TIZI-OUZOU', 36.7, 4.05, 13.77142857] ]; google.maps.event.addListener(mgr, 'loaded', function() { for (var i = 0; i &lt; locations.length; i++) { var marker = new google.maps.Marker({ position: new google.maps.LatLng(locations[i][1], locations[i][2]), }); mgr.addMarker(marker, 5); } mgr.refresh(); }); } google.maps.event.addDomListener(window, 'load', initialize);</code></pre> <pre class="snippet-code-css lang-css prettyprint-override"><code>html, body, #resultcnn { height: 100%; width: 100%; margin: 0px; padding: 0px }</code></pre> <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://maps.googleapis.com/maps/api/js"&gt;&lt;/script&gt; &lt;script src="http://google-maps-utility-library-v3.googlecode.com/svn/trunk/markermanager/src/markermanager.js"&gt;&lt;/script&gt; &lt;div id="resultcnn"&gt;&lt;/div&gt;</code></pre> </div> </div> </p>