Background. This study was designed to evaluate left and right ventricular performance using Tei indices in patients with severe chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy (PTE). The Doppler-derived indices are easily measurable indicators of ventricular function based on nongeometric assessment, which helps overcome some of the difficulties entailed in the geometric assessment of left ventricular (LV) and right ventricular (RV) function in pulmonary hypertension. Methods. The indices were derived for 24 patients (aged 54 ± 14 years) before and after PTE. Calculation of these indices was based on the duration of two time intervals using the formula (A − B)/B, where A is the interval between cessation and onset of mitral inflow (or tricuspid inflow) and B is LV or RV ejection time. In addition, LV and RV end-diastolic and end-systolic chamber areas were determined using two-dimensional echocardiography, and systolic function was calculated. Mean pulmonary artery pressure was determined invasively. Results. PTE led to a significant reduction of mean pulmonary artery pressure (46 ± 10 versus 25 ± 6 mm Hg; p < 0.05). LV and RV indices were abnormally high before surgery, declined significantly afterwards, and then almost matched normal values (0.61 ± 0.26 versus 0.37 ± 0.18; p < 0.05 and 0.55 ± 0.22 versus 0.37 ± 0.13; p < 0.05). Geometric assessment of the left and right ventricle also showed impaired systolic function before PTE, with significant improvement after surgery. Conclusions. LV and RV Tei indices allow a quantitative assessment of ventricular function in patients undergoing PTE. Lower indices after surgery reflect an improvement of the previously impaired cardiac function. Our results emphasize the value of PTE in the treatment of chronic thromboembolic pulmonary hypertension.