Prova questo codice: DEMO
Codice HTML:<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<style>
#mioIFRAME{
border:0px hidden;
width:100%;
}
</style>
<script>
function ridimensiona(){
var F = document.getElementById("mioIFRAME");
var h = window.outerHeight;
F.height = h+"px";
}
</script>
</head>
<body>
<iframe id="mioIFRAME" src="http://en.wikipedia.org/wiki/" frameborder="0" onload="ridimensiona()"></iframe>
</body>
</html>
prova anche a vedere qui ...

