Fifty nine patients who had been admitted to Seoul National University Hospital from April to October in 1986 were prospectively examined by a pulsed Doppler echocardiography on one day before cardiac catheterization. The sample volume was placed both just proximal and distal to pulmonic valve on 2-D echocardiogram. 1) Among the three morphologic patterns of the flow velocity, triangular and intermediate types indicate pulmonary hypertension (sensitivity 84%, specificity 86%), and round type indicates normal pulmonary arterial pressure (sensitivity 86%, specificity 84%). 2) In the group with pulmonary hypertension acceleration time and ejection time were measured shorter (P<0.01), and prejection period was measured longer than the group without pulmonary hypertension (P<0.05). 3) The best correlation was obtained between PEP/AT and mean pulmonary arterial pressure (r=0.77). Acceleration time alone also correlated well with mean arterial pulmonary pressure(r=-0.69). 4) In STI measurement and its correlation with pulmonary arterial pressure, no significant difference was observed when recorded in main pulmonary artery or right ventricular outflow tract. But in the latter position, late, systolic fluttering and variation in curve morphology occured less likely. 5) Our results indicate that the pulsed Doppler echocardiography is useful not only in the diagnosis of pulmonary hypertension but also in the quantitative estimation of pulmonary arterial pressure in different heart diseases. Futhermore this method may be a good tool for follow-up evaluation after surgical or medical treatment of patients with pulmonary hypertension.