trovatoooooooooooo, si che si può:

The Code
In the head of your document enter the following JavaScript code:

<script language="JavaScript">
<!--
function calcHeight()
{
//find the height of the internal page
var the_height=
document.getElementById('the_iframe').contentWindo w.
document.body.scrollHeight;

//change the height of the iframe
document.getElementById('the_iframe').height=
the_height;
}
//-->
</script>

and in the body create the iframe tag:
<iframe width="700" id="the_iframe"
onLoad="calcHeight();"
src="testing_page.shtml"
scrolling="NO"
frameborder="1"
height="1">
An iframe capable browser is
required to view this web site.
</iframe>

devo capire ancora che vuol dire tutto sto popò di codice però funziona