Four patients with Cushing's disease were treated with bromocriptine, administered three times daily, in doses ranging from 7.5 to 15 mg/day, during an average period of 80 days. Daily urinary 17-hydroxycorticosteroids (17-OHCS) and 17-ketosteroids (17-KS) excretion was measured during dynamic tests and at two-week intervals. Plasma adrenocorticotropic hormone (ACTH) and cortisol levels were also assayed before and after therapy. A marked clinical and laboratory improvement was noted in two patients, in another some clinical and laboratory improvement was obtained only after bromocriptine dosage was increased to 15 mg/day. There was no effect in the fourth patient. Thus, at least for a short period of time, bromocriptine may be useful therapy for some patients with Cushing's disease.