Background: Pulmonary hypertension (PH) is an important complication in the natural history of chronic obstructive pulmonary disease (COPD) and is caused by the remodeling of pulmonary arteries impairing the distensibility and stiffness of the major pulmonary arteries. Objectives: To evaluate the pulmonary artery distensibility by transthoracic echocardiography in patients with COPD. Method: We prospectively investigated COPD male patients and compared with healthy controls. In addition to right ventricle (RV) conventional echocardiographic parameters, right pulmonary artery fractional shortening (RPA-FS) and new pulmonary artery stiffness (PAS) parameters were compared. Results: Fifty-four COPD patients participated in the study and compared with a control group consisting of 24, all men, healthy, nonsmoking subjects. Six patients were excluded from study due to poor quality of echocardiographic recordings. The distensibility of PA evaluated by the RPA-FS parameter was found to be significantly lower in patients with COPD than it was in normal subjects (13.3 +/- 8.1 vs. 27.6 +/- 4.9, P :< 0.001) and correlated positively with tricuspid annular systolic excursion (TAPSE) (r = 0.566, P < 0.001) and pulmonary acceleration time (r = 0.607, P < 0.001) and correlated inversely with pulmonary artery systolic pressure (r = -0.587, P < 0.001), PAS(r = -0.479, P < 0.001) and functional capacity (r = -0.586, P < 0.001). Similar to this, PAS found to be impaired in COPD patients (29.5 +/- 13.6 vs. 15.7 +/- 4.1, P < 0.001) and correlated inversely RPA-FS (r = -0.479, P < 0.001). There were statistically significant difference for pulmonary artery distensibility (RPA-FS) and PAS parameters among the COPD subgroups with regard to NYHA functional capacity (P < 0.001). Conclusion: In this study, we found that PAS and distensibility were worsened in COPD patients and correlated with decreased functional capacity.