The relation between accuracy of 3-dimensional echocardiography (3DE) in determining left ventricular end-diastolic volume, end-systolic volume, and ejection fraction (compared with magnetic resonance imaging) and the number of component planes used for 3DE ventricular reconstruction was evaluated in 41 adult subjects with normal (n = 24) and abnormal (n = 17) left ventricles. Accuracy and confidence of 3DE gradually increased with use of additional component planes, so that > or = 10 planes from both parasternal and apical windows provided 3DE reconstructions that accurately predict magnetic resonance imaging-measured left ventricular volumes and ejection fraction with confidence.