Screening programs for early diagnosis of breast cancer and particularly, for its prevention are not feasible at present, because when the neoplastic mass becomes clinically observable it has already been quietly evoluting for many years. Besides the clinical examination, the self examination of the breast (B.S.E.) is therefore the only way to detect breast cancer at the earliest possible clinical stage. This study aimed at evaluating the average knowledge of this method among 2530 women who came to the centre for prevention and early diagnosis of tumours at the U.S.L. 61 Savigliano over the first half of 1981. We examined the relationship existing between some parameters and the B.S.E. as well as the reason why some women, though knowing about the S.E. do not perform it. We finally give some indications for a correct education to the B.S.E.