You could use frameset as the previous answer states but if you are insistent on using iFrames, the 2 following examples should work:
<body style="margin:0px;padding:0px;overflow:hidden">
<iframe src="http://www.youraddress.com" frameborder="0" style="overflow:hidden;height:100%;width:100%" height="100%" width="100%"></iframe>
</body>
An alternative:
<body style="margin:0px;padding:0px;overflow:hidden">
<iframe src="http://www.youraddress.com" frameborder="0" style="overflow:hidden;overflow-x:hidden;overflow-y:hidden;height:100%;width:100%;position:absolute;top:0px;left:0px;right:0px;bottom:0px" height="100%" width="100%"></iframe>
</body>
To hide scrolling with 2 alternatives as shown above:
<body style="margin:0px;padding:0px;overflow:hidden">
<iframe src="http://www.youraddress.com" frameborder="0" style="overflow:hidden;height:150%;width:150%" height="150%" width="150%"></iframe>
</body>
Hack with the second example:
<body style="margin:0px;padding:0px;overflow:hidden">
<iframe src="http://www.youraddress.com" frameborder="0" style="overflow:hidden;overflow-x:hidden;overflow-y:hidden;height:150%;width:150%;position:absolute;top:0px;left:0px;right:0px;bottom:0px" height="150%" width="150%"></iframe>
</body>
To hide the scroll-bars of the iFrame, the parent is made overflow: hidden
to hide scrollbars and the iFrame is made to go upto 150% width and height which forces the scroll-bars outside the page and since the body doesn't have scroll-bars one may not expect the iframe to be exceeding the bounds of the page. This hides the scrollbars of the iFrame with full width!