<script language="javascript" type="text/javascript"> function TDisplay(elementID) { var CurrentElement = document.getElementById(elementID); CurrentElement.style.display = (CurrentElement.style.display != 'none') ? 'none' : ''; return false; } </script>
.ASPX Page
<asp:LinkButton ID="LinkButton1" runat="server" OnClientClick="return TDisplay('panel1');"> Toggle Display(On / Off)</asp:LinkButton> <asp:Panel ID="panel1" runat="server"> Panel content here! </asp:Panel>