In order to improve the poor prognosis of advanced breast cancer cases with positive parasternal lymph nodes metastasis, prophylactic oophorectomy was performed in 25 unselected cases. In a retrospective study on the breast cancer cases operated on from 1958 to 1969, comparison of eight advanced breast cancer cases with positive parasternal lymph nodes metastasis after radical mastectomy of Halsted type and parasternal lymph nodes dissection with, and 17 cases without prophylactic bilateral oophorectomy was made with respect to the survival rate, the survival time pattern by Mantel-Haenszel's procedure in their entirety and the recurrence rate. These results suggest the effectiveness of prophylactic oophorectomy for the advanced breast cancer.