Parkinson's disease (PD) is thought to be caused by a combination of unknown environmental, genetic and degenerative factors. Among these factors, monoamine oxidase has been considered as a possible factor in the pathophysiology of Parkinson's disease. We have carried out allelic association studies of PD with monoamine oxidase type A (MAOA) and monoamine oxidase type B (MAOB) gene loci using dinucleotide repeat polymorphisms. Distributions of all alleles at MAOA and MAOB gene loci were almost similar in patients and controls. Contrary to previous reports, our findings could not support the hypothesis that susceptibility to PD is associated with MAOA or MAOB polymorphism.