To determine the diagnostic accuracy of pulmonary artery to aorta ratio in screening for pulmonary hypertension in advanced chronic obstructive pulmonary disease (COPD) patients.A prospective, diagnostic study was conducted in University Hospital Center Zagreb between January 2015 and March 2018. The study enrolled 100 patients who consecutively underwent chest computed tomography (CT), echocardiographic exam, and right heart catheterization. Two independent observers measured pulmonary artery and ascending aorta diameters. The correlation between the ratio and mean pulmonary artery pressure, measured invasively, was assessed. Patients with echocardiographic signs of moderate systolic or diastolic left ventricular dysfunction were excluded (n=44).Sixty-six patients (55.5% men), with a median age of 61, were identified. Median forced expiratory volume during the first second (FEV1) was 34±12, FEV1/forced vital capacity <0.70. Patients with and without pulmonary hypertension had pulmonary artery diameter of 36±7 mm and 27±4.6 mm, respectively (P<0.001). Median pulmonary artery/aorta (PA/A) ratios for patients with and without pulmonary hypertension were 1.05 and 0.81, respectively (P<0.001). PA/A ratio above 0.95 was an independent predictor of pulmonary hypertension with a specificity of 100% and a sensitivity of 74.51% (area under the curve=0.882; standard error=0.041; P<0.001).PA/A ratio as measured on chest CT images can be used as a screening tool instead of echocardiography.