Cross-sectional echocardiography was performed on 108 healthy children (7 days - 17 years old) and 55 children (6 months -16.5 years old) with interatrial communication. Right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, muscle volume, and the ratio of muscle to cavity were calculated on the basis of outlined cavity and myocardium of an apical four-chamber view. In the normal subjects right ventricular end-diastolic volume, end-systolic volume, stroke volume and muscle volume correlated with body surface area (end-diastolic volume: y=12.5x+7.8x(2), r=0.99; end-systolic volume: y=4.8x+3.6x(2), r=0.98; stroke volume: y=7.7x+4.2x(2), r=0.98; muscle volume: y=14.1x+2.9x(2), r=0.97), muscle/cavity ratio (0.85+/-0.17) and ejection fraction (58.9 +/- 6.2%) were unrelated to body surface area. In the subjects with interatrial communication, the right ventricular volumes were significantly larger (p<0.001) than the normal values with a linear relationship to the ratio of pulmonary to systemic flows. Right ventricular volumes can be determined in normal children with acceptable repeatability using a standard apical four-chamber view. The growth related normal values provide a basis for future quantitative studies.