Objective: This study was undertaken to evaluate the effect of Enalaprilat infusion on hemodynamics and renal function during cardiopulmonary bypass (CPB). Methods: Thirty adults undergoing CPB were randomly allocated into 2 groups. All patients received the same anesthetic protocol and same dopamine infusion protocol (2 mg/kg -1/min-1) during the study. In addition to dopamine infusion 15 patients received enalaprilat infusion (0.06 mg/kg-1/hr-1) during CPB. Blood creatinine, urea levels, and creatinine clearance (CLcr) were measured and cardiac output (CO) was calculated by echocardiography preoperatively and on the 6th postoperative day. Mean arterial pressure (MAP), central venous pressure (CVP), systemic vascular resistance (SVR) measurements were recorded during the operation and during postoperative 24 hours. Results: In the control group postoperative blood creatinine and urea levels were significantly higher and CLcr measurements were significantly lower than the preoperative values (p<0.05). These values did not change in the enalaprilat group. Mean arterial pressure was similar in both groups (p>0.05), but SVR was lower (p<0.05) and CVP was higher (p<0.05) in the enalaprilat group than in the control group. In the enalaprilat group postoperative CO measurements were higher than the preoperative values (p<0.05). Conclusion: Our results demonstrate that enalaprilat infusion during CPB improves renal function and CO measurements in the early postoperative period.