Pulmonary endarterectomy (PEA) is an established method for treatment of chronic thromboembolic pulmonary hypertension (CTEPH). MRI is currently proposed as novel tool for treatment monitoring. We evaluated 2D phase-contrast (PC) MRI of the main pulmonary artery as perioperative monitoring method in relation to cardiac and parenchymal perfusion MRI as well as to clinical parameters. 32 CTEPH patients who underwent MRI before and after PEA were analyzed. Results show improved postoperative pulmonary hemodynamics. 2D PC MRI data correlate well with cardiac as well as perfusion changes and clinical parameters which makes this method a simple tool for treatment monitoring after PEA.