<p>How do I go about doing this with jQuery?</p>

<p>Basically the structure:</p>

<pre><code>&lt;form id="myForm"&gt;
  &lt;iframe&gt;
    &lt;!-- Normal HTML headers omitted --&gt;
    &lt;input type=radio name="myRadio" value=1&gt;First
    &lt;input type=radio name="myRadio" value=2&gt;Second
    &lt;input type=radio name="myRadio" value=3&gt;Third
  &lt;/iframe&gt;
  &lt;input type=button value="Submit" /&gt;
&lt;/form&gt;
</code></pre>

<p>I tried various examples from the net such as </p>

<pre><code>$("input[@type=radio][@checked]");
</code></pre>

<p>But failed. Even with jQuery form plugin's <a href="http://malsup.com/jquery/form/#fields" rel="nofollow noreferrer">.fieldValue()</a> failed.</p>

Try
```
$('#myForm iframe').contents().find('input[name=myradio]').val()
```
I'll assume that the iframe contents have already been loaded and are accessible e.g same domain.