A cohort of 17,633 white males age 35 and older responded to a mailed epidemiological questionnaire in 1966 and was followed until 1986 to determine the risk of cancer associated with diet, tobacco use, and other factors. During the 20-year follow-up, 149 fatal prostate cancer cases were identified. Relative risks for prostate cancer were significantly elevated among cigarette smokers (relative risk, 1.8; 95% confidence interval, 1.1-2.9) and users of smokeless tobacco (relative risk, 2.1; 95% confidence interval, 1.1-4.1). No significant associations were found with frequency of consumption of meats, dairy products, fruits, or vegetables. There were no overall significant associations between consumption of vitamin A from animal sources (retinol) and provitamin A from plant sources (carotene) and risk, but positive trends were seen for ages under 75, while inverse associations were found at older ages. Beverage consumption, including drinking coffee and alcohol, was unrelated to risk. Marital status, education, rural/urban status, and farming residence were also unrelated to the risk of fatal prostate cancer. The findings add to limited evidence that tobacco may be a risk factor for prostate cancer, but fail to provide clues to dietary or other risk factors.