The records of all patients in whom a mastectomy was performed for carcinoma of the breast at this clinic during a recent two year period were reviewed, and the gross specimens were re-examined to study the incidence of cancerous involvement of the nipple and areola and related local clinical findings. Cancer was present in the nipple or areola, or both, in 12.2 per cent of the specimens. When the nipple and areola were clinically normal, involvement of the nipple and areola by carcinoma was rare if the primary tumor was less than 2 centimeters in diameter and was not situated behind the areola.