OBJECTIVE Portal hypertension is a common syndrome characterized by a chronic increase of the portal pressure and is the most frequent clinical manifestation of cirrhosis. In this study short term effects of Valsartan, an angiotensin II receptor antagonist, upon portal blood flow in 36 cirrhotic patients was determined by Doppler ultrasonography. METHODS Patients were divided into three groups of 12 according to Child-Pugh classification. They (18 women and 18 men with a mean age of 50+/-14 years) received a daily dose of 80 mg valsartan for one week after which the effects upon hemodynamic changes were evaluated by colored Doppler ultrasonography. Hemodynamic measurements were performed 24 hours prior to valsartan administration and then four and eight days after adiministration. The following parameters were evaluated: for hemodynamic changes: peak systolic flow velocity, diastolic flow velocity, peak systolic flow velocity/diastolic flow velocity ratio, resistive index and pulsatility index were evaluated in hepatic, superior mesenteric and right and left renal arteries. In the portal vein, diameter, mean flow velocity and flow volume were evaluated. Results are expressed as means+/-SD. RESULTS Hemodynamic parameters showed no significant change during the measurement in hepatic, superior and right and left renal arteries. Valsartan induced a significant decrease (p<0.05) in portal vein diameter, in portal vein maximal flow velocity and in portal vein flow volume. The decrease in portal vein flow volume was 11.7% on day four and 24.4% on day eight. In two patients, a symptomatic hypotensive attack occurred. Serum potassium levels were increased significantly (p<0.05). CONCLUSIONS These results indicate that valsartan can be used in portal hypertension safely.