Background. The prevalence of posttransplant hypertension is high, and it appears to be a major risk factor for graft and patient survival. The aim of this study was to assess the efficacy and safety of valsartan, an angiotensin-receptor blocker (ARB), in the treatment of posttransplant hypertension. Methods. A multinational, multicenter, prospective, randomized, double-blind, placebo-controlled study was performed on the treatment of hypertension (systolic blood pressure [BP] ! 140 and/or diastolic BP >= 90 mm Hg) in adult cyclosporin-treated renal transplant recipients randomized to receive either valsartan (80 mg once daily) or a matching placebo for 8 weeks. After the first 4 weeks, furosemide 20 mg twice daily was added on a open basis if systolic BP remained : 130 mm Hg and/or diastolic BP remained ! 85 mm Hg. Results. One hundred fifteen (valsartan = 57, placebo = 58) uncontrolled hypertensive patients despite monotherapy for hypertension, other than angiotensin-converting enzyme inhibitor or ARB, were randomized. In the valsartan group, significant decreases were seen in systolic BP (from 153 +/- 11 to 140.9 +/- 18.35 mm Hg at 4 weeks, and 136.5 +/- 15 mm Hg at 8 weeks) and diastolic BP (from 93 9 to 85.2 +/- 11.28 mm Hg at 4 weeks, and 83.8 +/- 9.2 mm Hg at 8 weeks). There was no significant change in the placebo group. In the valsartan group, a statistically but not clinically significant reduction was observed in the mean hemoglobin concentration (12.9 +/- 1.6 g/dL versus 13.8 +/- 1.6 g/dL at 4 weeks, P <.01; and 12.3 +/- 1.6 versus 13.8 +/- 1.7 at 8 weeks; P <.001) as well as a significant increase in serum potassium (4.4 +/- 0.5 mmol/L versus 4.1 +/- 0.4 mmol/L at 4 weeks, P <.01) vs placebo. Conclusions. Valsartan is effective in the treatment of posttransplant hypertension and is well tolerated.