Pimozide, a specific blocker of dopaminergic receptors, was administered orally to 10 adult male volunteers for 4 days. Half of the subjects received 4 mg/day and the other half 2 mg/day. Blood samples were obtained the day before,the 4th day of Pimozide, and 4 days after the last dose of the drug for the determination of LH, FSH, GH, PRL, TSH, cortisol and testosterone levels. Twenty-four h urinary collections were obtained for the determination of LH and FSH levels. Plasma LH levels decreased and plasma PRL levels increased in the combined groups during Pimozide. Plasma TSH levels decreased during treatment in the 4 mg group only. Urinary LH and plasma testosterone levels decreased in the post-treatment period in the combined groups. These data support the concept of a dopaminergic control of the secretion of several hormones in the human.