ClamXav is a free virus scanner for Mac OS X. It uses the very popular ClamAV open source antivirus engine as a back end and has the ability to detect both Windows and Mac threats.

ClamXav can be setup up as passive or active: scan only the files you tell it to or your entire hard drive, whichever you prefer; you can also choose to activate Sentry to monitor your hard drive and scan new files as they arrive.
Introducing ClamXav 2

Clean, simple-to-use interface
Clearly lists infected files
Free virus definitions (usually updated daily)
Save your favourite scan locations for easy access
Customise the toolbar - or hide it entirely
Send selected files to quarantine or trash with one click
Specify files to exclude using plain text* or by using drag & drop from the Finder
Specify schedules to update virus definitions and perform scans
Use ClamXav Sentry to monitor your hard drive and scan new files as they arrive†
Use the bundled ClamAV engine or bring your own installation†
Compatible with Mac OS X 10.6, 10.7, 10.8 and OS X 10.9 Mavericks


http://www.clamxav.com/