Background: pulmonary vascular resistance (PVR) is the most important postoperative parameter that drops dramatically after pulmonary thromboendarterectomy (PTE). It determines whether the endarterectomy procedure was successful and the presence of postoperative residual pulmonary hypertension. Objectives: To measure predictors of postoperative PVR and residual pulmonary hypertension. Patients and Methods: Through a prospective and retrospective study, 20 patients underwent PTE between June, 2019 and April, 2021. Results: Postoperative PVR was affected by delay for surgery after diagnosis, preoperative PaO₂, preoperative PVR and cardiac index. Conclusion: Better results can be obtained with early surgery, higher preoperative PaO₂ and cardiac index, and lower preoperative PVR.