 <p>Others have already told you that what you've asked for isn't possible, as HTML attributes must be plain text, not more HTML.</p> <p>They've also told you that there are Javascript and JQuery libraries which will help you do what you're wanting to do. There are loads of scripts you could use, here's a link to one that you might want to try: <a href="http://bassistance.de/jquery-plugins/jquery-plugin-tooltip/" rel="nofollow">http://bassistance.de/jquery-plugins/jquery-plugin-tooltip/</a></p> <p>However, I feel I should add one further point which others have missed, and which is actually quite important:</p> <p><strong>You're using the wrong attribute.</strong></p> <p>The <code>alt</code> attribute is <em>not</em> the correct attribute to use for a hover tooltip effect. You should be using the <code>title</code> attribute for this.</p> <p>Using <code>alt</code> works this way for historic reasons in some browsers (I believe it works in IE, but not much else), but it is <em>not</em> intended as a tooltip. The correct use of <code>alt</code> is for a small bit of descriptive text that will appear if the image is not loaded. This could be because the file failed to load, or the user has images turned off, or the user has a text-to-speech browser, etc, but if the image is displayed, then this text should never be displayed.</p> <p>The <code>title</code> attribute on the other hand is intended to be displayed, and all browsers implement it as a tooltip (in fact, it's not just on <code>&lt;img&gt;</code> tags; you can use <code>title</code> for <em>any</em> element).</p> <p>Hope that helps.</p>