Doppler sonography is frequently obtained in patients with chronic liver disease, patients with suspected portal hypertension, and patients with known portal hypertension. In this clinical setting, it is important to understand both the normal hemodynamics of the liver and the morphological and hemodynamic changes that occur with portal hypertension. Among the many findings of portal hypertension are enlargement of the portal vein, decreased portal vein velocity, increased congestion index, development of portosystemic collaterals, and reversal of portal vein flow. The most important portal systemic collaterals to focus on with Doppler are the coronary vein and the umbilical vein. Using all of these clues, it is possible to diagnose portal hypertension with a high degree of sensitivity and specificity in most patients.