In an attempt to elucidate the dopaminergic involvement in the regulation of the effect of angiotensin II on the adrenals, plasma aldosterone response to angiotensin II infusion (5 ng/kg/min, for 60 minutes) was studied in five normal volunteers in various experimental conditions. Prior infusion of dopamine (3 micrograms/kg/min) or saline (1000 ml/hour) caused an attenuation of the aldosterone response to angiotensin II. Concurrent infusion of a dopaminergic antagonist, metoclopramide (10 micrograms/kg/min), abolished the inhibitory effect of dopamine and saline. These results suggest that the dopaminergic mechanism is involved in the adaptive aldosterone response of the adrenal to acute saline loading in man.