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A method is described for the purification to homogeneity of the DOPA-decarboxylase present in the integument of blowfly larve. The enzyme has a M_r of 90,000–96,000 and is composed of two subunits of M_r 50,000 and 46,000. The enzyme decarboxylates DOPA and is practically inactive towards 5-hydroxytryptophan, tryptophan, tyrosine, and phenylalanine. Enzyme activity is enhanced by Al³⁺ and Mn²⁺ and is depressed by Cu²⁺ and Hg²⁺. N-Acetyldopamine is a competitive inhibitor of the decarboxylase.