The putative association between pesticide exposures and Parkinson's disease (PD) remains controversial. We identified all subjects who developed PD in Olmsted County, Minnesota, from 1976 through 1995, and matched them by age (+/- 1 year) and sex to general population controls. We assessed exposures to chemical products by means of telephone interview with cases, controls, or their proxies (149 cases; 129 controls). Exposure to pesticides related or unrelated to farming was associated with PD in men (odds ratio, 2.4; 95% confidence interval, 1.1-5.4; P = 0.04). The association remained significant after adjustment for education or smoking. Analyses for the other six categories of industrial and household chemicals were all nonsignificant. This population-based study suggests a link between pesticides use and PD that is restricted to men. Pesticides may interact with other genetic or nongenetic factors that are different in men and women.