PURPOSE: Breast cancer in men is uncommon; 1500 new cases are diagnosed in the United States yearly. Optimal management of breast cancer in men is unknown because the rarity of the disease precludes large randomized trials. A review of the literature was undertaken with emphasis on articles published over a 10-year period. DATA SOURCES: Articles published between 1942 and 2000 on breast cancer in men were identified by using CancerLit, MEDLINE, and study bibliographies. STUDY SELECTION: All retrospective series and studies focusing on the epidemiology, risk factors, genetics, and pathology of breast cancer in men. DATA EXTRACTION: Data on the epidemiology, risk factors, genetics, pathology, molecular markers, prognostic factors, therapy, and outcomes of breast cancer in men. DATA SYNTHESIS: Carcinoma of the male breast accounts for 0.8% of all breast cancers. Risk factors include testicular disease, benign breast conditions, age, Jewish ancestry, family history, and the Klinefelter syndrome. BRCA2 mutations predispose men to breast cancer and may account for 4% to 14% of all cases. Pathology data were reviewed: 81% of tumors were estrogen receptor positive, 74% were progesterone receptor positive, 37% overexpressed c-erbB-2, 30% overexpressed p53, 79% overexpressed Bcl-2, 51% overexpressed cyclin D1, and 39% overexpressed epidermal growth factor receptor. Prognostic factors include tumor size, histologic grade, and lymph node status; survival is similar to that of breast cancer in women when patients are matched for age and stage. Adjuvant hormonal therapy and chemotherapy, using the same guidelines as for women, are recommended for men. Hormonal therapy is the primary therapy for metastatic disease; chemotherapy should be reserved for hormone-refractory disease. CONCLUSION: Breast cancer is similar in men and women; however, breast cancer in men is more frequently hormone receptor positive and may be more sensitive to hormonal therapy.