Atrial natriuretic peptide (ANP) has been shown to reverse functional impairment in ischemic acute renal failure (ARF). To prolong and/or to enhance the effects of peptide, in this investigation dopamine (D) (3 micrograms/kg BW/min) was applied together with ANP (100 ng/kg BW/min) after 90 min unilateral renal artery occlusion in anesthetized dogs. ANP significantly increased creatine clearance, filtration fraction, diuresis, sodium excretion, sodium reabsorption, and free water clearance, as in postinfusion period only V remained elevated. D alone did not effect renal function beneficially. ANP+D improved kidney function impairment to a level comparable with that of ANP alone, but V and UNa.V remained increased in the postinfusion period. MAP was elevated during ANP+D infusion as compared to ANP alone and was sustained to the end of the experiment. We conclude that D does not potentiate the positive effects of ANP on postischemic kidney, but prolongs its action on UNa.V, possibly by maintenance of high MAP after renal ischemia.