The education of the public to look on any mass in the breast as a potentially serious condition is leading to more satisfactory treatment of the neoplastic lesions of this organ. Granted, however, that every mass in the breast is to be considered malignant by the laity until proved otherwise, the physician must be able, within reasonable limits, to differentiate between the benign and the malignant new growths. Certainly tuberculosis of the breast holds a definite place among the benign conditions of this organ which must be differentiated from the malignant. The number of cases, however, remain small as compared with the number of cases of neoplasm and no one group of cases of mammary tuberculosis has been large enough in itself to allow of general statements or definite conclusions. The number of cases proved by microscopic examination and completely reported in the literature probably is now sufficient, when reviewed