Non-infiltrating intraductal carcinoma may be considered a type of "carcinoma in situ" of the breast. In a review of 47 cases diagnosed and treated at Gustave-Roussy Institute between 1956--1972, it appears that the early symptoms of this rare type of breast carcinoma (it occurs only in 2.4% of all breast cancers) were a bloody discharge (38%) or Paget's disease of the nipple (11%). The histological examination was of the utmost importance in these cases due to the diagnostic uncertainties between benign hyperplastic lesions and authentic carcinomas as well as between infiltrating carcinomas and strictly intraductal carcinomas. Frozen section was only accurate in 30% of cases. The high frequency of multicentric foci (76%) contrasted with the absence of lymph node involvment (none of the 23 cases in which at least one node was excised, showed lymph node metastases). Treatment was only of ablation of the whole mammary gland, except in 6 patients who had a tumorectomy, two of whom also received radiotherapy. Local recurrence occurred in 4 patients, 3 of whom had only tumorectomy. The contralateral breast was affected in 2 cases. No patient under follow-up died of cancer within 5 years. The peculiar and highly favorable course of non-infiltrating intraductal carcinoma calls for an adequate therapy which could later be followed by a plastic reconstructive surgery should the patient wish to have this procedure.