It is known that in some families an association exists between breast and prostate cancer. Several reports have suggested that BRCA2 mutations may be associated with an increased risk of these cancers. Herein, we report three cases of early onset of prostate cancer in families with female and male breast cancers. In each case, the familial phenotype is associated with a mutation of the BRCA2 gene. More generally, genetic counseling, including screening for BRCA2 mutations, should become standard practice in kindred with prostate and breast cancers.