In clinical treatment of children with congenital heart disease (CHD) assessment of right ventricular (RV) function is important. Available imaging techniques have been of limited value because of technical factors and the complex geometry of the right ventricle. To validate magnetic resonance (MR) imaging measurements of RV function in children, gradient echo MR imaging of both ventricles and MR flow mapping of great vessel and tricuspid flow was performed in 20 children with CHD affecting the right ventricle and in 22 healthy children ranging in age from 5 to 16 years. Close correlation between RV versus LV stroke volumes (r = 0.96) and RV stroke volume versus great artery (r = 0.97) or tricuspid flow (r = 0.97) was observed with small interobserver and intraobserver variability. Results of healthy children were end-diastolic volume: 70 +/- 9 ml/m2, end-systolic volume: 21 +/- 5 ml/m2, and ejection fraction: 70% +/- 4%. In the patient groups clinically important differences were noted. We conclude that MR imaging provides accurate noninvasive measurements of RV function in healthy children and patients with (operated) CHD.