I have tried clamav and Avast, and must say that for me Avast is preferable. It runs much lighter and there have not been any false positives to date - except for instance my Ubuntu OS .iso which is listed as a "decompression bomb" but I think that is to be expected. (Compressed archives). To install Avast on Ubuntu:- 1) Download the deb file http://www.avast.com/eng/avast-for-linux-workstation.html 2) Get the free registration code. 3) Install. 4) To get the icons in Applications menu:- cd /usr/lib/avast4workstation/share/avast/desktop sudo ./install-desktop-entries.sh install 5) Launch Avast and enter code. 6) Run a scan. ... Or better, run one of these commands in the terminal: avast -ar*Scan (where -a is the default scan all files/archives and -r*Scan outputs the results to the file 'Scan'. The * includes results that are OK). sudo avast -cr*Scan (as above but really thorough and therefore also somewhat slower). I usually go to the directory I want to scan and just right click> 'Open in Terminal' and then enter the command(s) .. (nautilus-open-terminal is a package available in Synaptic). Type man avast for all the details pertaining to usage. The GUI is self explanatory, you can exclude files etc. etc. PS. I scan rarely and mainly before sending something by email to friends using Windows. Regards.