BACKGROUND: Although narrative reviews have concluded that there is strong support for familial clustering of prostate carcinoma, the association has never systematically been quantified in reviews. The purpose of this meta-analysis was to summarize and quantify the recurrence risk ratio with emphasis on the degree of relation, the specific relationship of the family member, the number of affected family members, and the age at diagnosis. METHODS: Publications were identified through computerized database searches for epidemiologic studies published up to December 2002. In addition, references cited in original and review papers were examined. Three blinded reviewers extracted both qualitative and quantitative information from each paper. Using random effects meta-regression analyses, the authors calculated summary recurrence risk ratios (S(lambda)). The reviewers also evaluated changes in S(lambda) according to differences in study methodology. RESULTS: Thirty-three epidemiologic studies were included in the current review. S(lambda) was 2.53 (95% confidence interval, 2.24-2.85) for first-degree family members. S(lambda) appeared to be greater for men with an affected brother than for men with an affected father. S(lambda) for men who had second-degree relatives with prostate carcinoma was only slightly elevated. The nature of the familial clustering is such that S(lambda) increases with decreasing age of the patient and family members, with increasing genetic relatedness of the affected relative, and with increasing number of individuals affected within a family. CONCLUSIONS: The studies that were reviewed consistently demonstrate that family history is a significant risk factor for development of prostate carcinoma.