Substituted gold(III) tetraarylporphyrins have been synthesised. The analogues TPPAuCl (TPP = tetraphenylporhyrin), MeOTPPAuCl, TMOPPAuCl, MeO2CTPPAuCl, O2NTPPAuCl and PyTPPAuCl were evaluated for their in vitro cytotoxic activity against the Sarcoma 180 mouse tumour cell line panel. Compound MeO2CTPPAuCl exhibited good growth inhibitory properties against Sarcoma 180 and afforded IC50 values <3μM for 92.386% of the cell lines in the panel. Compounds MeOTPPAuCl and TPPAuCl were effective inhibitors of tumour cell growth, but generally less effective than MeO2CTPPAuCl as cytotoxic agents.