Chronic thromboembolic pulmonary hypertension (CTEPH) is a major cause of chronic pulmonary hypertension leading to right heart failure and death. Ventilation/perfusion single photon emission computed tomography (V/Q SPECT) is the screening test of choice showing mismatch in at least one segment or two sub-segments. Our aim was to investigate the relationship between the extent of pulmonary perfusion defects and hemodynamic, echocardiographic, biological and functional parameters. Between 2012 and 2019, 46 patients with CTEPH were retrospectively enrolled in the study. The diagnosis of pulmonary hypertension was made by the referral team of the expert center according to the European guidelines. All patients underwent pulmonary V/Q SPECT, right heart catheterization, transthoracic echocardiography (TTE), functional tests and natriuretic peptides assays. There was a slight correlation between the extent of pulmonary perfusion defects and pulmonary vascular resistances (R=0.510, P < 0.001). However, there was no correlation between the extent of pulmonary perfusion defects and NYHA stage, NT-proBNP level, functional parameters (6 minutes-walk distance-6 MWD), right ventricular function assessed by TTE. Pulmonary perfusion defects extension by V/Q lung SPECT are correlated with pulmonary vascular resistances in CTEPH. However, it is not correlated with right ventricular function and functional parameters.