Is javascript the only way? I didn't see any topics in the MSDN, so I take it because RadioButtonList is not a single entity, you cannot set focus to it?
Give it an ID, don't set runat="server", and after the element has loaded set focus() to it. yo can set focus to any element as long as it has an ID - then document.getElementById("IDName").focus();
Why not to set runat="server"? I guess your reason is that then the client-side ID depends on the place of the control within the pages control tree, that is, you do not know its ID. Right? There's an easy work-around for this: override OnPreRender, and there register a JavaScript block onto the page where you declare a JavaScript var that has the ClientID of the server control. Then, using that var you can get the getElementById to work no matter what the actual client ID turns out to be.
Well, you can obtain programatically the clientid of controls but I didn't know if you wanted to go that route