Should I Install Anti-Virus Software On My Mac?
The short answer is no, you do not need anti-virus protection on a Mac.
There aren't currently any active viruses for the Mac. Anti-virus software only protects against known issues, so even if you had the software and a new Mac virus was unleashed, the software would not be able to stop it.
The couple of times that Macs have run into virus issues, Apple has immediately squashed them via free Software Updates.
If you buy anti-virus software for the Mac, it is most likely looking on your system for Windows viruses and then deleting them. Windows viruses cannot work or do any damage on a Mac. This software just eliminates the chance of you spreading them (via email, etc.) from your Mac to a Windows users. Since they offer little to no protection to you, it is a waste of money to buy anti-virus software for your Mac.