Nineteen examples of a very rare type of carcinoma of the breast have been studied. The carcinoma is unusual in that it has exaggerated secretory features previously reported only (with one exception) in juveniles. But not all the patients in our series were juveniles; they ranged in age from 9 to 69 years (median age, 25 years). Six were 30 years of age or older. Eighteen patients were female and 1 was a 9-year-old boy. Treatment varied from local excision of the tumor to radical mastectomy. Four of the 11 patients who had axillary node dissection had metastatic deposits showing the same secretory features as the primary neoplasm. One of these 4 patients, a 25-year-old woman, died within ten months with disseminated tumor. Because this distinctive pattern of carcinoma is not limited to children and adolescents, we propose that it be called "secretory carcinoma." Since, of the 19 patients, 4 (21%) had axillary node metastases and 1 (5%) died with disseminated tumor, an extended simple mastectomy is recommended as the initial treatment for patients more than 20 years of age.