Hello Friend,

Try this:

<Script language = JavaScript>
function validate() {
if(document.f1.choose.selectedIndex==""){
    alert ( "Please select Dropdown value!" );
     return false;  
    }
    if ( ( document.f1.radios[0].checked == false ) && ( document.f1.radios[1].checked == false ) ){
        alert ( "Please choose Radio Button!" );
        document.f1.radios[0].focus();
        return false;
    }
return true;
}
</SCRIPT>
</HEAD>

<form name="f1" onsubmit ="return validate();">
<SELECT name = choose>
<OPTION VALUE = "select">select</OPTION>
<OPTION VALUE = "NE" >North East</OPTION>
<OPTION VALUE = "NW">North West</OPTION>
<OPTION VALUE = "SE">South East</OPTION>
<OPTION VALUE = "SW">South West</OPTION>
<OPTION VALUE = "Midlands">Midlands</OPTION>
</SELECT>

<input type="radio" name="radios" value="male">Male <input type="radio" name="radios" value="Female">Female<br /><br />
<input name="Submit" value="Send" type="submit" >

</form>

Thanks