The records of 432 patients with breast cancer who underwent surgical castration during the years 1955 through 1967 were reviewed to determine whether subsequent pelvic difficulty justified hysterectomy. Cases of oophorectomy alone were compared with those of oophorectomy and hysterectomy. The following factors were considered: age, operative complications, incidence of ovarian metastases, uterine pathology, blood transfusions, duration of anesthesia, postoperative vaginal bleeding, and morbidity and mortality rates. Morbidity was slightly higher and hospitalization slightly prolonged in patients undergoing hysterectomy. As to uterine pathology, a high proportion of the uteri were abnormal and some had malignant disease. The likely incidence of subsequent pelvic problems after oophorectomy alone was assessed as 1 in 25. Hysterectomy is probably indicated in all patients with breast cancer undergoing castration, except in those with a poor operative risk due to extensive metastatic disease.