Background— Acute renal failure is a serious complication of cardiac surgery causing high morbidity and mortality. The aim of this study was to evaluate the usefulness of fenoldopam, a specific agonist of the dopamine-1 receptor, in patients at high risk of perioperative renal dysfunction. Methods and Results— A prospective single-center, randomized, double-blind trial was performed after local ethical committee approval and after written consent was obtained from 80 patients undergoing cardiac surgery. Patients received either fenoldopam at 0.05 μg/kg per minute or dopamine at 2.5 μg/kg per minute after the induction of anesthesia for a 24-hour period. All these patients were at high risk of perioperative renal dysfunction as indicated by Continuous Improvement in Cardiac Surgery Program score >10. Primary end point was defined as 25% creatinine increase from baseline levels after cardiac surgery. The 2 groups (fenoldopam versus dopamine) were homogeneous cohorts, and no difference in outcome was observed. Acute renal failure was similar: 17 of 40 (42.5%) in the fenoldopam group and 16 of 40 (40%) in the dopamine group ( P =0.9). Peak postoperative serum creatinine level, intensive care unit and hospital stay, and mortality were also similar in the 2 groups. Conclusions— Despite an increasing number of reports of renal protective properties from fenoldopam, we observed no difference in the clinical outcome compared with dopamine in a high-risk population undergoing cardiac surgery.