Dear All, If you are looking for close the ISDGL=1 Sharepoint dialog box on button click on C# here is the code for it Add following script files in to ascx file for open popup! <Sharepoint:ScriptLink runat="server" Name="SP.UI.Dialog.js" Localizable="false" ID="s4" LoadAfterUI="true"/> This script will set the properties of popup window <script> function openPop_up(pageURL, title, dlgwidth, dlgHeight) { var options = { url: pageURL, title: title, allowMaximize: false, showClose: true, width: dlgwidth, height: dlgHeight, dialogReturnValueCallback: Function.createDelegate(null, function(result, returnValue) { ...