Apocrine tumors from the axilla of 12 patients were studied clinically and pathologically. Based on histologic features, two tumors were classified as adenomas and ten as adenocarcinomas. All of the neoplasms were characterized by a glandular arrangement of large cells with abundant eosinophillic cytoplasm and evidence of decapitation secretion. The cytoplasm of the tumor cells contained PAS-positive, diastase-resistant granules. Intracytoplasmic particles of iron were demonstrable in three of ten tumors. Follow-up was available for all 12 patients. The two patients with apocrine adenoma are alive and well. Two patients with adenocarcinoma died of unrelated causes shortly after diagnosis. Of the remaining eight patients with adenocarcinoma, three have died of disease, and one is living with skeletal metastasis. A correlation appears to exist between tumor differentiation and prognosis.