The purpose of this study is to determine the need of education about BSE for the medical members, to survey about the performance and the knowledge of BSE in patients who operated on subtotal and total mastectomy and to compare the regularity of BSE with the severity of breast cancer. The subjects were 163 patients with operated on mastectomy who participated were interviewed in the S university Hospital. The collected data were analyzed by descriptive statistics and t-test, One-way ANOVA and Pearson Correlation with SPSSWIN program. Results were obtained as follows: 1. There was no statistical difference between in the regular group of the mammography and the regular BSE group(F=0.558, P=0.458). 2. There was statistical difference between the method of detection and the severity of the breast cancer(F=3.359, P=0.011). 3. There was statistical difference between regularity of the BSE and the severity of breast cancer(F=3.301, P=0.019). 4. There was showed higher severity of the breast cancer in the elderly patients(r=0.172, P=0.019). 5. There was showed higher severity of the breast cancer in the lower educational level(r=-0.170, P=0.033). According to this study need to the development of the educational program about the BSE and the future research about the regular BSE of the high risk group in the breast cancer.