How to Set RadioButtonFor() in ASp.net MVC 2 as Checked by default

Use the simple way:

<%= Html.RadioButtonFor(m => m.Gender, "Male", new { Checked = "checked" })%>

It's not too pretty, but if you have to implement only very few radio buttons for the entire site, something like this might also be an option:

<%=Html.RadioButtonFor(m => m.Gender,"Male",Model.Gender=="Male" ? new { @checked = "checked" } : null)%>