Goals: We aimed to determine the role of thorax high-resolution computed tomography (HRCT) in demonstrating the pulmonary vasodilatation in patients with hepatopulmonary syndrome (HPS). Background: Traditionally, the presence of intrapulmonary vascular dilatations can be detected by using one of the three diagnostic modalities: contrast-enhanced echocardiography, technetium 99 m-labeled macroaggregated albumin scan, and pulmonary angiography. Study: The study group included 10 patients with HPS (Group 1), 12 patients with normoxemic cirrhosis (Group 2), and 12 healthy controls (Group 3). All of the subjects underwent conventional and HRCT of thorax. The diameters of pulmonary trunk, main pulmonary arteries, and right lower lobe basal segmental arteries were measured. The ratios of right lower lobe basal segmental pulmonary artery to bronchus diameter were calculated. Results: The mean diameters of the main pulmonary trunk, right and left main pulmonary arteries were not different between the groups. Mean diameters of right lower lobe basal segmental pulmonary arteries were significantly higher in Group 1 compared with Group 2 (P = 0.01) and Group 3 (P = 0.002). Mean right lower lobe basal segmental pulmonary artery to bronchus ratios were significantly higher in Group 1 compared with Group 2 (P = 0.03) and Group 3 (P < 0.001). Group 2 had significantly higher pulmonary artery to bronchus ratios than Group 3 (P < 0.001). Conclusions: Thorax HRCT may be helpful in the diagnosis of HPS by demonstrating the dilated peripheral pulmonary vessels or increased pulmonary artery to bronchus ratios in patients with liver disease and hypoxemia.