There is a widely held belief that breast carcinoma occurring in elderly women is characterized by a relatively favorable prognosis and unusual histologic types of tumors. To assess these topics in a single patient group, 169 women (greater than or equal to 75 years) treated by mastectomy for primary operable breast carcinoma at Memorial Hospital (1964 to 1970) were identified. Followup revealed that 117 patients (70 percent) died. Thirty-eight women (22 percent) developed recurrent breast carcinoma and 35 (21 percent) were known to have died of the disease. Death was attributable to a cause other than breast carcinoma in 82 cases (49 percent). Remaining alive were 48 patients (28 percent) including 3 with recurrent carcinoma. Four patients (2 percent) were lost to followup. The age-adjusted survival experience of our elderly breast cancer patients was significantly poorer than that of a standard population when compared by the life table method. This difference appeared largely to reflect the mortality effect of breast cancer. Median times to recurrence (25 mo) and to death from breast carcinoma (27 mo) were not prolonged. Pathologic analysis revealed that some tumor types with a relatively favorable prognosis (mucinous, papillary, infiltrating lobular) occur more often in elderly women. However, this probably has little bearing on overall prognosis in the group since infiltrating duct carcinoma which constitutes nearly three-quarters of the tumors was responsible for 86 percent of deaths due to breast carcinoma.