FIRS may refer to:
Federal Inland Revenue Service, the federal tax administrator in Nigeria Fédération Internationale de Roller Sports, the International Federation of Roller Sports FIRS (index), a share index of the Banja Luka Stock Exchange Forensic Investigation Research Station, a "body farm" at Colorado Mesa University Forum of International Respiratory Societies, a respiratory health advocacy organization Front of Islamic Revolution Stability, principlist political group in Iran
See also FIR (disambiguation) The Firs (disambiguation)