Determination of pulmonary artery systolic pressure (PASP) is essential for the diagnosis, and the timing and type of management of patients with congenital heart disease (CHD). Usually cardiac catheterization, an expensive and invasive technique, is required for accurate measurement. A number of noninvasive methods for the assessment of PASP have been developed, one of which is estimation of PASP using contrast-enhanced tricuspid regurgitation Doppler signals (TRDS). In this study, right ventricular systolic pressures (RVSP) and PASP of 36 patients (19 girls, 17 boys; aged 5 months to 15 years) with CHD were estimated by TRDS before and after galactose solution (GS) and were compared with catheterization measurements. Significant TRDS (> 1 m sec.) were obtained in nine of 36 (25%), patients before GS and in 23 of 36 patients (64%) after GS. TRDS were increased significantly by contrast agent. Estimated RVSP and PASP were significantly different from the measured pressures before and after GS. There were significant correlations between the estimated RVSP and PASP and measured RVSP after GS. Estimated pressures were underestimated. We conclude that it is better to use the estimated PASP on patients with significant TRDS for the classification of PASP.