The role of alpha 2-adrenoceptors in the regulation of basal prolactin secretion was investigated in healthy male volunteers. Two independent, placebo-controlled, double-blind experiments were performed. In the first experiment, 50 micrograms dexmedetomidine (MPV-1440), a selective alpha 2-adrenoceptor agonist, and saline placebo were infused (IV) in five subjects. In the second experiment, 100 mg atipamezole (MPV-1248), a selective alpha 2-adrenoceptor antagonist, and saline placebo were infused in six volunteers. The concentrations of prolactin in plasma were not affected by the drugs. These results suggest that alpha 2-adrenoceptors do not a play significant role in the control of basal prolactin secretion in healthy men.