Experience with 50 women undergoing extracranial transethmoidal-sphenoidal hypophysectomy for metastatic breast carcinoma with 12-month follow-up showed an objective remission of metastases after hypophysectomy in 58% of patients. The highest incidence of remission following the operation occurred in those women with only osseous metastases (83%) or with previous remission to both therapeutic oophorectomy and androgen administration (86%). No patient with primary central nervous system metastases, only one of ten with hepatic metastases, and none who had failed to respond to both oophorectomy and exogenous androgen administration experienced remission after hypophysectomy. The operative approach to the pituitary was via a periorbital incision, the posterior ethmoid cells, and the sphenoid sinus. Cerebrospinal fluid rhinorrhea occurred in three early patients, and has been successfully avoided in later ones by a fascia lata graft. Diabetes insipidus, seen in 13 patients, and extraocular palsies, seen in two, were transient.