A matched case-control study was conducted to test the hypothesis that prostate cancer is associated with employment in the compounding area of a rubber and tire manufacturing plant. A search of death certificates from the years 1964 to 1975 led to the identification of 88 cases of prostate cancer. These were individually matched with 258 controls on the factors of age, race, and date of entry into the plant. To eliminate possible confounding by sociodemographic differences, several variables were assessed but none differed significantly between cases and controls. The batch preparation work area showed statistically significant (p < 0.025) risk ratios over three exposure periods -- more than one month, more than 24 months, and more than 60 months. The service to batch preparation and shipping and receiving work areas showed significant risks for blacks. The data were used to assess a latent period or etilogic fraction for prostate cancer for those employed in batch preparation. Twenty-nine years was estimated to be the latent period while the period of greatest risk occurred during the years 1940 to 1947.