Tyrosinase (EC 1.14.18.1) was isolated from Penicillium chrysogenum. Aqueous extracts from 4 plants namely Moringa oleifera (family: Moringaceae), Mentha piperita (family: Lamiaceae), Coriandrum sativum (family: Apiaceae) and Thymus vulgaris ((family: Lamiaceae) were prepared and their inhibitory effect was evaluated. Coriandrum sativum extract was the most potent one in tyrosinase inhibition (81.6 %) whereas the Mentha piperita extract was the least effective (55.4%). Analysis of the total phenolics and the total flavonoids indicated that the highest content of phenolic compounds and flavonoids were in Coriandrum sativum whereas the highest content of tannin was found in Moringa oleifera. These results revealed that the inhibition of tyrosinase activity by the various plant extracts was correlated with the content of the total phenols, total flavonoids and tannin content. The inhibition of tyrosinase by these plant extracts indicates a promising therapeutic potential for treatment of melanogenesis.