diff --git a/HISTORY.md b/HISTORY.md
index a8d1a024e..1ecee1135 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -2,7 +2,15 @@
 http://visjs.org
 
 
-## 2014-10-16, version 3.5.0
+## not yet released, version 3.5.1
+
+### DataSet
+
+- Event listeners of `update` now receive an extra property `data`, 
+  containing the changed fields of the changed items.
+
+
+## 2014-09-16, version 3.5.0
 
 ### Network
 
@@ -15,7 +23,7 @@ http://visjs.org
 - Fixed dataAxis not showing large numbers correctly.
 
 
-## 2014-10-12, version 3.4.2
+## 2014-09-12, version 3.4.2
 
 ### Network
 
@@ -25,7 +33,7 @@ http://visjs.org
 - Fixed minor bug in positioning of fontFill of nodes with certain shapes.
 
 
-## 2014-10-11, version 3.4.1
+## 2014-09-11, version 3.4.1
 
 ### Network
 
diff --git a/docs/dataset.html b/docs/dataset.html
index 57010e1d4..17d2ab131 100644
--- a/docs/dataset.html
+++ b/docs/dataset.html
@@ -448,8 +448,10 @@ <h3 id="Callback">Callback</h3>
       In case of the events <code>add</code>,
       <code>update</code>, and <code>remove</code>,
       <code>properties</code> is always an object containing a property
-      items, which contains an array with the ids of the affected
-      items.
+      <code>items</code>, which contains an array with the ids of the affected
+      items. The <code>update</code> event has an extra field <code>data</code>
+      containing the original data of the updated items, i.e. the gives the
+      changed fields of the changed items.
     </td>
   </tr>
   <tr>
diff --git a/lib/DataSet.js b/lib/DataSet.js
index d22a5c04b..d05658480 100644
--- a/lib/DataSet.js
+++ b/lib/DataSet.js
@@ -204,10 +204,11 @@ DataSet.prototype.add = function (data, senderId) {
  * @return {Array} updatedIds     The ids of the added or updated items
  */
 DataSet.prototype.update = function (data, senderId) {
-  var addedIds = [],
-      updatedIds = [],
-      me = this,
-      fieldId = me._fieldId;
+  var addedIds = [];
+  var updatedIds = [];
+  var updatedData = [];
+  var me = this;
+  var fieldId = me._fieldId;
 
   var addOrUpdate = function (item) {
     var id = item[fieldId];
@@ -215,6 +216,7 @@ DataSet.prototype.update = function (data, senderId) {
       // update item
       id = me._updateItem(item);
       updatedIds.push(id);
+      updatedData.push(item);
     }
     else {
       // add new item
@@ -254,7 +256,7 @@ DataSet.prototype.update = function (data, senderId) {
     this._trigger('add', {items: addedIds}, senderId);
   }
   if (updatedIds.length) {
-    this._trigger('update', {items: updatedIds}, senderId);
+    this._trigger('update', {items: updatedIds, data: updatedData}, senderId);
   }
 
   return addedIds.concat(updatedIds);