We used a pulsed Doppler technique to examine the flow velocity pattern in the right ventricular outflow tract in 33 adults. In the patients with normal pulmonary artery pressure (mean pressure less than 20 mm Hg, 16 patients), ejection flow reached a peak level at midsystole (137 +/- 24 msec, mean +/- SD), producing a domelike contour of the flow velocity pattern during systole. In contrast, the flow velocity pattern in patients with pulmonary hypertension (mean pressure greater than or equal to 20 mm Hg, 17 patients) was demonstrated to accelerate rapidly and to reach a peak level sooner (97 +/- 20 msec, p less than .01); in 10 of the pulmonary hypertensive patients a secondary slower rise in flow velocity was observed during a deceleration, resulting in the midsystolic notching. The time to peak flow (acceleration time, AcT) and right ventricular ejection time (RVET) were measured from the flow velocity pattern. Either AcT or AcT/RVET decreased with increase in mean pulmonary artery pressure, and a very high correlation (r = -.90) was found between AcT/RVET and log10 (mean pulmonary artery pressure). The use of this technique permitted the noninvasive estimation of the pulmonary artery pressure.