Purpose: The diagnosis of Budd-Chiari syndrome on CT is difficult if CT do not demonstrate obstruction of theIVC or hepatic vein and other parameter is needed for the correct diagnosis. The purpose of our study was todetermine the usefulness of measuring the diameter of azygos-hemiazygos vein on CT to differentiate Budd-Chiarisyndrome from advanced liver cirrhosis. Materials & Methods: Fourteen patients who were proven as Budd-Chiarisyndrome on vena cavography were studied for analysis. All patients showed evidence of liver cirrhosis on CT. As acontrol group fifteen cases of advanced liver cirrhosis who underwent endoscopic sclerotheraphy due to esophagealvariceal bleeding were also included for comparison. The largest short axis diameter of azygos-hemiazygos vein wasmeasured in all patients at the level of diaphragm on axial CT and the results were compared in both groups.Results: In patients with Budd-Chiari syndrome the largest short axial diameter of azygos-hemiazygos vein rangedfrom 0.5cm to 2.5cm(mean;1.5cm). Only one patient who showed hepatic venous obstruction demonstrated a diameter ofless than 1cm(0.5cm). In contrast, the diameter in patients with advanced liver cirrhosis without obstruction ofIVC or hepatic vein was less than 1cm with a range from 0.2cm to 1cm(mean;0.6cm). Conclusion: The short axisdiameter of azygos-hemiazygos vein was an indicator of IVC obstruction(Budd-Chiari syndrome).