The role of genetics in Parkinson's disease (PD), previously controversial, is now supported by several studies. A major breakthrough has been the discovery of a single gene defect in familial Parkinson's disease. A single base pair change at position 209 from G to A (G209A) in the fourth exon of the alpha-synuclein gene has been identified in cases of familial PD. We looked for this mutation in 65 cases of sporadic PD in Taiwan Chinese patients but found none of these patients with this mutation. We conclude that mutation of G209A in the alpha-synuclein gene plays no role in sporadic PD among Taiwan Chinese.