Growth hormone release-inhibiting hormone (GHR-IH) was administered to five patients with abnormal pituitary-adrenal function. There was immediate suppression by about 50% of ACTH levels in two patients who had undergone bilateral adrenalectomy because of Cushing's disease; one of them had Nelson's syndrome. Bromocryptine (2-5 mg) suppressed ACTH levels by 62-67% for more than 6 h in these patients. GHR-IH did not significantly influence cortisol secretion by an adrenal carcinoma and only slight changes were seen in two patients with Addison's disease. The possible therapeutic implications are discussed.