Background/Aims: Propranolol can prevent variceal bleeding by ameliorating portal hypertension. We conducted this study to determine the effect of propranolol on portal hypertension and the optimal required dose in Korean cirrhotic patients. Methods: This study prospectively evaluated 50 patients with cirrhosis who exhibited variceal bleeding. The hepatic venous pressure gradient (HVPG), portal venous flow, heart rate (HR), and blood pressure were assessed both at baseline and at 3 months after the treatment. The initial dose of propranolol (20 mg) was subsequently adjusted until the target HR was reached. Patients in whom HVPG reduced by ＞20% or to less than 12 mmHg were defined as responders. Results: Propranolol significantly (p＜0.01) reduced the HVPG (-21±26%, mean±standard deviation), portal venous flow (-25±21%), HR (-20±13%), and blood pressure (-3±13%). Twenty-nine patients were responders, and the optimal required dose was 154.4 mg. The main complication was dizziness (24%), but this was not serious enough to require medication withdrawal. Conclusions: Propranolol is safe and effective at reducing portal pressure in Korean cirrhotic patients. An effective improvement in portal hypertension requires the dose to be increased until the target HR is reached. (Gut and Liver 2007;1:159-164)