Hypertrophy of the uterus, hyperplasia of the endometrium with mucous polyps, and simple cysts of the ovaries, were found at operation where the pre-operative diagnosis was menorrhagia due to a uterine fibroid. The 49-year-old patient had had advancing acromegaly 7 years, an enlarged sella, but normal cata-menia. The hyperplasia is interpreted as a hitherto unrecorded expression of visceral splanchnomegaly characterizing this disease, and resembles changes in the genital tract of dogs with experimentally produced acromegaly. It is assumed the acromegaly was due to an eosinophilic adenoma in no way affecting the function of the basophilic cells in which are localized the gonad-stimulating substance, and that the genital hyperplasia was a direct effect of the activity of the eosinophilic adenoma. The similarity between the genital system in this patient, in whom there was presumably an increased secretion of the growth-promoting substance alone, and the genital hyperplasia induced experimentally in dogs by alkaline extracts of the anterior lobe containing predominantly growth-promoting substance, indicate that the growth-promoting principle may produce marked hyperplasia of the genital tract in the female.