Mutation in UCH-L1 has been reported as a rare cause of autosomal dominant Parkinson's disease (PD). A S18Y polymorphism in the same gene has been associated with sporadic PD. We investigated the frequency of this polymorphism among the Han-Chinese ethnic population in a case–control study. A total of 600 patients with PD and 334 unrelated healthy controls were genotyped using PCR-restriction fragment length polymorphism analysis. We did not observe any difference in allele or genotype frequencies between the cases and the controls ( P > 0.05). Our results do not support a role for this variant in sporadic PD.