A 39 year old woman with primary amenorrhoea and increased excretion of gonadotrophins, developed a chromophobe adenoma in the pituitary gland. Only a few years before she died, the diagnosis of Cushing''s disease was made which progressed despite hypophysectomy. Evidence is given for the conclusion, that the patient suffered from ovarian dysgenesis, which secondarily led to hyper-function and tumor formation of the pituitary gland and also to development of Cushing''s disease. It is concluded that patients with hypogonad-ism should be observed for pituitary tumor formation, and that adequate substitution therapy may prevent formation of pituitary tumors.