Objective To study the accuracy and practical value in the clinical diagnosis of Budd-Chiari syndrome by B ultrasonography and postcaval vein contrast examination.Methods 42 patients received B ultrasonographic scanning of the postcaval vein and the liver before the use of angiography.Angiography included Seldinger single-direction postcaval intubation(14 cases) and double-direction intubation(28 cases),and quick photographic observation.Results B ultrasonography showed that 18 cases had postcaval segmental or membranous obstruction 24 cases had postcaval stricture at its opening,and 20 cases complicated with single right hepatic stricture,8 cases with left vein stricture and 12 cases with central hepatic caval stricture.Communicating branched vessels were formed among 16 cases between hepatic vessels were formed among 8 cases between hepatic left-middle,and middle-right hepatic veins each.Reticular communicating vessels were formed in 8 cases between left middle and right.5 cases had slight postcaval stricture and their blood flowed non-obstructedly postcaval veinography showed 12 cases had postcaval stricture at proximal end,28 cases total segmental or membranous obstruction.There were 8 cases respectively for hepatic central vein and right hepatic vein development each.The remaining 26 cases had no hepatic venous development.There were 30 cases who had obvious branched circulaltion formation,and even their branched circular vessels had tumous-like expansion.Conclusion B ultrasonography,as a way of easy,and no-trauma examination,is the first-choice means to screen the patients.Postcaval angiography is a means to diagnose Budd-Chiari syndrome,which is neccessary for the cases with total segmental or membranous obstruction to have double-direction postcaval angiography,especially for the cases to have interventive therapy.