The trick is same as that of Internet Explorer. Well, in this case it can be done using an Firefox extension called Flashblock.

WARNING:- Never install this extension, if your Firefox version is below 1.5 and in such a case, upgrade the browser and then install this plugin.

Restart the browser and you will be amazed to see, the flash ads being blocked. This plugin also has the option to exempt some sites (likeonline greeting sites etc) from block.

And this Firefox extension successfully blocks the following:

  • Macromedia Flash

  • Macromedia Shockwave

  • Macromedia Authorware

To know more about this firefox extension, please visit