The natural history and current management of carcinoma of the breast in men is reviewed. Articles published from 1942 to 1992 on the natural history, clinical manifestations, diagnosis, and treatment of carcinoma of the breast in men were identified using CANCERLINE and MEDLINE. Carcinoma of the breast affects approximately 1000 men per year in the United States; 300 men per year will die of metastatic disease. The mean age at diagnosis is 59 years. The causes of breast cancer in men are unknown. The most common clinical manifestation of breast cancer in men is a painless, firm subareolar mass or a mass in the upper outer quadrant of the breast. Diagnosis can be confirmed by fine-needle aspiration or surgical biopsy. Infiltrating ductal carcinoma is the predominant histologic type. Treatment is similar to that of women with breast cancer. Men with axillary nodal metastasis should receive adjuvant systemic combination chemotherapy or tamoxifen, or both, after primary surgical treatment. Because most men with carcinoma of the breast have estrogen- and progesterone-receptor-positive tumors, distant metastatic disease should be treated initially with hormonal therapies. The epidemiology, prognostic factors, survival by stage, pattern of metastasis, and response to treatment in men are similar to those in women with breast carcinoma. The data suggest, however, that breast cancers in men are more likely to respond to hormonal manipulation.