Today cancer of the breast is the most frequent fatal carcinoma of women. To detect breast carcinoma at an early stage, it is necessary to do mass screening and not to wait until women detect a nodule by chance in their breasts. In the last 2 years 530 women with diagnostically uncertain breast tumours were seen in the outpatient department, 79 of them turned out to be carcinomatous. From 1966 to 1975 246 women underwent a Halsted-Rotter procedure for breast carcinoma. The average age, histological findings and rate of survival are analysed.