Parkinson's disease (PD) rates were examined by province and by sex for Canada for the years 1979-1984. As seen with other studies, PD displayed an uneven geographic distribution in the average annual prevalence rates for both males and females. The distribution of prevalence rates indicated a higher prevalence of PD in the western-most provinces. Nationally, males had a statistically significantly higher prevalence than females. Three provinces displayed a statistically significant sex difference with 2 provinces having a higher prevalence rate among males and 1 with a higher prevalence among females. The uneven distribution of prevalence rates offers some support for the involvement of environmental influences in the etiology of PD.