Methods for treating Parkinson's disease (PD) are provided. Recombinant adeno-associated virus (rAAV) virions are used to deliver genes encoding dopamine-synthesizing enzymes to the central nervous system of a primate. Once delivered, the genes are expressed, which then results in dopamine synthesis and amelioration in the clinical signs and symptoms of PD. The methods of the present invention can be used to deliver the three central dopamine synthesizing enzymes: tyrosine hydroxylase, aromatic L-amino acid decarboxylase, and guanosine triphosphate cyclohydrolase I thereby enhancing dopamine biosynthesis and providing for enhanced therapeutic efficacy.