Breast carcinoma is the commonest cancer in women. Segregation analyses support the existence of a major susceptibility gene with a dominant pattern of inheritance in 4 to 10% of cases. Three genes involved in the genetic predisposition to breast tumors have recently been identified: BRCA-1 associated with early onset familial breast cancer and breast/ovarian carcinoma syndrome, p53 associated with Li-Fraumeni syndrome, and the androgen receptor gene in male breast cancer with Reinfenstein syndrome. A better understanding of inherited contribution may have important implications for screening individuals at high-risk in families.