This study was performed to compare the amount of blood flow from left and right side heart using Doppler echocardiography and Fick method. The pulmonary blood flow (Qp), aortic blood flow (Qs) and Qp/Qs ratio were noninvasively evaluated by two dimensional Doppler echocardiography in 10 patients with ventricular septal defect in children, aged 2 years to 15 years (mean+/-SD=7.1+/-4.9 years). Cardiac catheterization was performed within 2 days after examination of Doppler echocardiography in all patients. Systemic and pulmonary blood flow was calculated by using Fick principle, based on measured oxygen consumption and measured blood oxygen saturation. The Doppler frequency shift was analyzed by computer system combined with Meridian Echocardiography System. Comparison of Qp, Qs and Qp/Qs ratio obtained by invasive methods and by two-dimensional pulsed wave Doppler echocardiography showed a correlation of 0.679 in Qp, 0.710 in Qs and 0.639 in Qp/Qs ratio (p<0.05).