Prolactin secretion was studied in 46 patients with Icenko-Cushing's disease in the acute stage, at the early and late terms of the treatment with khloditan and low doses of peritol and over a period of partial and clinical remission, resultant of the treatment with khloditan and high doses of peritol. The changes in the blood prolactin concentration were determined on the empty stomach by radioimmunoassay in the presence of insulin hypoglycemia and thyroliberin injection. It was found that the prolactin basal level in the blood of patients with Icenko-Cushing's disease remained elevated at the early and late terms of the treatment with khloditan and low doses of peritol and the adenohypophyseal reactivity to stimulants did not return to normal. Khloditan and high dose peritol treatment did not induce clinical and hormonal remission of the disease but resulted in the blood prolactin basal level increase and even more pronounced decrease in the adenohypophyseal reactivity to stimulants in comparison with those of the active stage of the disease. The blood prolactin concentration in patients with clinical remission lowered down to the level, being seen before the treatment, and the reactivity to stimulants significantly improved comparatively to that of the partial remission, but did not return to normal.