To assess the accuracy of pulsed and continuous-wave Doppler echocardiography (DE) for estimating pressure drops across right ventricular outlet obstruction, we examined 27 children (valvular pulmonary stenosis n = 16, complex congenital heart lesion with prior pulmonary banding n = 11). The Doppler evaluation was performed within 24 hours of cardiac catheterization in 17 patients, in 10 it was done 2-24 months (mean 12.2 months) after catheterization. We found a good correlation (r = 0.93) with slight underestimation of pulmonary valve gradient. Using three windows (left parasternal, suprasternal and subcostal) the ultrasound beam can be better aligned parallel to the excentric jet of a malformed valve than using the left parasternal position alone. In children with complex congenital heart disease and normally related great arteries Doppler ultrasound reliably estimates the gradient across a pulmonary artery band using the left parasternal transducer position (r = 0.92). In patients with malposition of the great arteries the use of multiple windows is necessary. Thus, DE provides an accurate noninvasive method of estimating pressure gradients in patients with right ventricular outflow obstructions and is helpful in determining the subsequent clinical management.