This study examined the association between Parkinson's disease (PD) and exposure to pesticides. A series of meta-analysis of peer-reviewed studies were performed, using 19 studies published between 1989 and 1999. Prior to the meta-analysis, all studies were reviewed and evaluated for heterogeneity and publication bias. Significant heterogeneity among studies was detected and combined odds ratio (OR) was calculated using the random effect model. The majority of the studies reported consistent elevation in the risk of PD with exposure to pesticides. The combined OR studies was 1.94 [95% confidence interval (95% CI) 1.49-2.53] for all the studies, and 2.15 (95% CI 1.14-4.05) for studies performed in United States. Although the risk of PD increased with increased duration of exposure to pesticides, no significant dose-response relation was established, and no specific type of pesticide was identified. Our findings suggest that exposure to pesticides may be a significant risk factor for developing PD.