Firefox does not have Ads included, so it is most likely either your home page, or some software (possibly a virus) that is making these adds appear. Try to run a few programs to remove any viruses: * [http://www.malwarebytes.org/mbam.php MalwareBytes' Anti-Malware] * [http://support.kaspersky.com/faq/?qid=208283363 TDSSKiller - AntiRootkit Utility] * [http://windows.microsoft.com/MSE Microsoft Security Essentials] (A good permanent anti-virus if you don't already have one) Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article. After that, Run a Firefox Reset: #Go to Firefox > Help > Troubleshooting Information. #Click the "Reset Firefox" button. #Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish. #Firefox will open with all factory defaults applied. Further information can be found in the [[Reset Firefox – easily fix most problems]] article. Then, finally, I suggest installing something like Ad-Block Plus to fully remove ads. [https://adblockplus.org .adblockplus.org]