The interaction of octacarboxylic metal phthalocyanines (MPc(COOH)8, M = Al(III) and Co(II) with bovine serum albumin (BSA) has been studied. From the binding isotherm based on spectrophotometric titration, the association constant and a number of ligands per binding site were calculated at 25°C. By using the well studied Hemin chloride (HE), Ibuprofen(IB) and L-tryptophan (TRP) as competitive ligands, the binding sites of AlPc(COOH)8 were found to be on domain I and II of BSA, while on domain I for Co(COOH)8.