We studied pulmonary venous (PV) flow patterns using Doppler echocardiography in 26 patients with ventricular septal defect less than 3 years of age. Fifteen patients had moderate or severe symptoms, and the remaining 11 had no significant symptoms. Peak velocity of PV diastolic flow and flow velocity integral of PV diastolic flow in the symptomatic patients were significantly larger than those in either asymptomatic patients or the normal controls. The ratio of PV diastolic flow velocity to PV systolic flow velocity and the ratio of flow velocity integral of PV diastolic flow to that of PV systolic flow in the symptomatic patients were significantly larger than those in either asymptomatic patients or the normal controls. The ratio of PV diastolic flow velocity to PV systolic flow velocity as well as the ratio of flow velocity integral of PV diastolic flow to that of PV systolic flow correlated with V wave in left atrial or pulmonary capillary wedge pressure and indexes of left ventricular mass and left atrial volume. We conclude that the abnormal pulmonary venous flow patterns in ventricular septal defect might be associated with large left-to-right shunting and left atrial pressure V wave.