Hypertension present in more than 50% of successfully renal transplanted patients and its prevalence has slightly increased since the introduction of cyclosporine A. Twenty patients, 9 women and 11 men aged from 30 to 58 years, with stable cadaveric renal allograft function and moderate to severe hypertension, were included in the study. Renal artery graft stenosis causing hypertension were excluded. All patients were given triple drug immunosuppressive treatment with methylprednisolone, azathioprine and cyclosporine A (CsA) and their hypertension was treated with a nifedipine dose of 20 mg twice daily. To evaluate the effect of ACE inhibitors on renal hemodynamics and hypertension, a 4 mg/daily dose of perindopril was added to the above regimen for two months. Effective renal plasma flow (ERPF) decreased from 208 +/- 54 to 168 +/- 61 ml/min and renal vascular resistance (RVR) increased from 75 +/- 12 to 88 +/- 17 mm Hg/ml/min (P < 0.05 and P < 0.01, respectively). Mean blood pressure was significantly (P < 0.001) reduced by the combination of both agents in comparison to the blood pressure control by monotherapy with nifedipine. It is suggested that the combination of both antihypertensive agents was more effective than monotherapy with nifedipine in controlling blood pressure, but less favorable on the renal hemodynamic response in hypertensive renal transplant patients who were maintained on CsA.