Higher plasma urate concentration has been linked to lower risk of Parkinson's disease in men, but data are lacking on women and African Americans. The authors examined plasma urate in relation to Parkinson's disease in the biracial, population-based Atherosclerosis Risk in Communities (ARIC) cohort. Between 1987 and 1989, 15,792 participants, aged 45-64 years, were recruited from 4 US communities and have since been followed with 3 triennial visits and annual surveillance. Plasma urate was measured at visits 1 and 2, and the concentrations were highly correlated. From visit 1 through 2004, 95 potential cases of Parkinson's disease were identified from multiple sources. Odds ratios and 95% confidence intervals were calculated from multivariate logistic regression models. Plasma urate concentration was inversely associated with Parkinson's disease occurrence. The odds ratios between extreme quartiles of plasma urate were 0.4 (95% confidence interval: 0.2, 0.8) in the overall analysis, 0.3 (95% confidence interval: 0.1, 0.7) for men, and 0.4 (95% confidence interval: 0.2, 1.0) for Caucasians. Such an association was also suggested among women and African Americans but was not statistically significant because of small sample sizes. These data support the previous finding that urate may be a protective factor against Parkinson's disease.