Javascript Example
Screen shot
Javascript radio button validation
<html>
<head>
<title>Javascript Example</title>
<script language=\"javascript\" type=\"text/javascript\">
function validate()
{
var str=true;

document.getElementById(\"msg\").innerHTML=\"\";

if(document.frm.gender[0].checked || document.frm.gender[1].checked)
{
str=true;
}
else
{
document.getElementById(\"msg\").innerHTML=\"Please select gender\";
str=false;
}

return str;

}
</script>
</head>

<body>
<form name=\"frm\" action=\"\" method=\"post\" onSubmit=\"return validate();\">
Male <input name=\"gender\" type=\"radio\" value=\"male\" />
Female <input name=\"gender\" type=\"radio\" value=\"female\" />
<div id=\"msg\" style=\"color:#FF0000\"></div>
<input name=\"btn\" type=\"submit\" value=\"submit\">
</form>
</body>
</html>

You can download source code here