L-DOPA is a useful drug for Parkinson's disease. This investigation deals with the biosynthesis of L-DOPA by parental (GCB-6) and mutant (UV-7) strains of Aspergillus oryzae. There was a marked difference between the mycelial morphology and pellet type of the parental and UV-irradiated mutant cultures. The mutant strain of Aspergillus oryzae UV-6 showed pellet-like mycelial morphology and improved tyrosinase activity. Mould mycelium was used for biochemical conversion of L-tyrosine to L-DOPA since tyrosinase is an intracellular enzyme. The mutant was found to give 3.72 folds higher production of L-DOPA than the parental strain. The comparison of kinetic parameters was also done which showed greater ability of the mutant to yield L-DOPA (i.e. Y_p/x 32.73 mg/mg with parent and 95.71 mg/mg with mutant). When cultures grown for various incubation periods, were monitored for Qp, Qs and qp, there was significant enhancement (p < 0.0025-0.005) in these variables by the mutant strain of Aspergillus oryzae UV-7 over GCB-6 on all the rates.