OBJECTIVE Cisapride, a benzimide derivative, is a gastrointestinal prokinetic agent without dopamine-antagonistic or cholinomimetic effects. This study aims at assessing the effect of cisapride oral administration on portal flow in patients with advanced post hepatitic cirrhosis using duplex Doppler ultrasound (US). METHODS A total of 12 patients with post-hepatitic liver cirrhosis were included in the study. Duplex Doppler sonographic examinations were performed before and after treatment. The subjects received 10 mg cisapride before starting the measurement procedure and then three times a day for 2 days. Portal haemodynamics including vessel diameters (mm), mean flow velocities (cm/s), blood flows (ml/min) were investigated. RESULTS Mean portal vein diameters, mean portal flow velocity and portal blood flow volume showed decreases of 18.6, 22.1 and 43.6% (P<0.001), respectively. After cisapride administration the portal vein diameter did not change in two patients and the portal vein velocity did not change in three patients. No significant change was found in systolic blood pressure, diastolic blood pressure or pulse rate after the administration of cisapride. CONCLUSIONS In this study, it was demonstrated that oral administration of cisapride results in a significant reduction of portal blood flow but there were no changes in heart rate or systolic pressure in patients with cirrhosis of the liver.