codice:
<input type="radio" name="prova" value="uno" onClick="togglebis(this);">
<input type="radio" name="prova" value="due" onClick="togglebis(this);">

 <div style="display:none;" id="sub1">sub1</div>
 <div style="display:none;" id="sub2">sub2</div>


<script>

function togglebis(radio){
if(radio.value=='due'){document.getElementById('sub2').style.display='block'; document.getElementById('sub1').style.display='none';}
else if(radio.value=='uno'){document.getElementById('sub1').style.display='block';document.getElementById('sub2').style.display='none';}
}

</script>