Two-dimensional and Doppler echocardiography can provide structural and hemodynamic information for patients with ventricular septal defects (VSDs). Therefore, two-dimensional and Doppler echocardiographic examinations were performed on patients with VSDs returning for the Second Natural History Study of Congenital Heart Defects.Five hundred fifty-six patients with VSDs underwent two-dimensional and Doppler echocardiographic examinations. Three hundred twenty-four patients were in the medically treated group, and 232 had undergone a previous operation. The location of the VSD was classified in 235 patients. Several Doppler measurements were used to calculate pulmonary artery pressures: tricuspid regurgitation peak systolic velocity, peak systolic velocity of VSD jet, pulmonary regurgitation end-diastolic velocity, and pulmonary artery acceleration time. The two methods that were found to be reliable consisted of the tricuspid regurgitation peak systolic velocity and the pulmonary regurgitation end-diastolic velocity. These measurements were obtained in only 26% of patients at all centers. At one center in which adult and pediatric echocardiography was performed in a single laboratory, these values were obtained in 60% of patients.Two-dimensional and Doppler echocardiography has the ability to provide a noninvasive method of assessing morphology and hemodynamics in patients with VSDs. However, the reliability and accuracy of hemodynamic measurements are dependent on operator experience.