People seem to have strong feelings about whether antivirus is needed on Android. I used Lookout and Bitdefender at different times on my Thunderbolt. Nothing bad to say about them, I just didn't see that either one did much, but I'm careful about what I download and install. If you stick to the major, well known markets, check reviews and pay attention to the permissions, you shouldn't have any problems. It isn't like my computer where I assume everything I download is dangerous and I decided that I can get along without an antivirus on my phone. I consider antivirus a category of app that may not be necessary, but if having one makes you feel better and it doesn't eat your battery, or use too much memory, get one. You can always uninstall it.