In order to study the effect of proton beam irradiation on prolactinoma cells and hypophyseal intact cells tests with i.v. administration of TRH (200 micrograms) and LH-RH (100 micrograms) were performed in 16 women with prolactin-secreting adenomas before and in 2 mos.-2 years after irradiation of the pituitary body with a high energy narrow proton beam (1000 MeV) at a dose of 40-120 Gy. A curative therapeutic effect of proton therapy which was low with respect to reproductive function recovery, was combined with lowered functional reserves of hypophyseal thyrotrophs and gonadotrophs. The informative value of the tests with the releasing hormones was shown for the determination of damage of hypophyseal intact cells. The results suggest refractivity of adenomatous lactotrophs to radiation exposure and the hypothalamic level of disorder of ovarian function regulation in this pathology.