A carbonic anhydrase IX (CA IX) inhibitor which comprises a compound of general formula: R&mdashNH&mdashCX&mdashNH&mdash(CH2)n&mdashAr-Q-SO2&mdashNH2 or a pharmaceutically-acceptable salt, derivative or prodrug thereof wherein n=0, 1 or 2 Q is O or NH X is O or S and R comprises an organic substituent group.