In this study, production of L-DOPA (L-3, 4-dihydroxy phenylalanine) was investigated by using tyrosinase enzyme in batch and packed bed reactors. Tyrosinase has been immobilized with method of entrapment in copper-alginate gels. L-DOPA concentration obtained from batch reactor for free and immobilized enzyme was 9.5 and 4.5 mg/L, respectively. L-DOPA concentration was obtained as 1.2 mg/L in the packed bed reactor. When air was introduced L-DOPA production increased 6.4 times in packed bed reactor and the productivity was calculated as 110mg/Lh. (c) 2006 Elsevier Inc. All rights reserved.