Tissue Doppler imaging (TDI) was used to obtain additional insight into the cardiac adaptation to severe pulmonary arterial hypertension. Pulmonary hemodynamics and right and left ventricular function were investigated in 18 untreated patients, 12 with pulmonary arterial hypertension and 6 with chronic thromboembolic pulmonary hypertension. Fourteen age-matched healthy subjects served as controls for TDI measurements. Pulsed TDI was determined using atrioventricular planes and strain and strain rate along the right ventricular free wall, ventricular septum, and left ventricular lateral wall from 4-chamber apical views. Patients had early diastolic dysfunction, with decreased E-wave peak velocity and increased isovolumic relaxation time, both more important in the right than left ventricle. Compared with controls, strain and strain rate decreased along the right ventricular free wall with a midapical predominance (midbasal strain rate 1.7 ± 0.6 vs 2.2 ± 0.5; p = 0.02; midapical strain rate 0.9 ± 0.9 vs 2.3 ± 0.7; p <0.001), but were preserved along the left ventricular lateral wall. Tricuspid E-wave and isovolumic relaxation time (R = 0.62, p = 0.006), as well as midapical (r = 0.65, p = 0.004), but not midbasal, right ventricular strain and strain rate correlated with mean pulmonary artery pressures. In conclusion, cardiac function was abnormal in patients with severe pulmonary hypertension because of a combination of alterations in both diastolic and systolic right ventricular function and left ventricular diastolic function. Only right ventricular dysfunction correlated with pulmonary artery pressures.