In this study, the kinetic parameters and inhibition mechanism of anti-tyrosinase activity of captopril were investigated in order to provide the basis for the development of novel effective tyrosinase inhibitor. The kinetic analysis showed that the inhibition of captopril on tyrosinase activity was competitive. The half-maximal inhibitory concentration (IC50) and inhibition constant (K-i) were estimated to be 590 mu g/mL and 294 mu M respectively. Furthermore, in vitro studies revealed that tyrosinase did not show any cytotoxicity or nonselective toxicity. These experimental results indicate that captopril may have the potential to be useful in cosmetics or food processing and therefore, it should be investigated further.