A population-based case-control study of prostatic cancer in Alberta was undertaken to determine the risk factors associated with the disease. Cases were 382 newly diagnosed prostatic cancer patients and 625 controls, group-matched to the anticipated age distribution of the cases, chosen at random from the health insurance roster. Subjects were interviewed in their homes by using a pre-tested questionnaire including questions related to ethnic group, education, puberty, marital history, family history, residence, water supply, smoking, and diet. Factors significantly related to the risk of developing prostatic cancer included ethnic group (British high, Ukrainian low), education (elementary high, university low), age at first marriage (early high, late low), family history (high risk for those with relatives with prostatic cancer), and increased masculinity among the children of cases. The results with respect to smoking, occupation, medical history, birthplace, residence, water supply, and diet were generally negative.