Budd-Chiari syndrome (BCS) is a disorder caused by occlusion of the hepatic vein or inferior vena cava. The clinical presentation include abdominal pain, hepatomegaly, ascites, leg edema, collateral venous dilatation of the body trunk, and portal hypertension. In addition, BCS can cause hepatocellular carcinoma (HCC) in some patients, although its pathogenesis is not yet completely understood. The average reported time lag from diagnosis of BCS to full-blown HCC ranges from several years to several decades. Hepatic carcinogenesis in patients with BCS perhaps reflects a prolonged and persistent liver injury in that it occurs in the primary inferior vena cava obstruction rather than the primary hepatic vein thrombosis. Among patients with BCS, membranous obstruction of the vena cava (MOVC) usually presents an insidious and chronic illness, whereas primary hepatic vein thrombosis presents an acute or subacute illness. We experienced a case of a patient with BCS, which progressed rapidly that HCC developed only nine months after the diagnosis of BCS. The factors causing this rapid progression are still unclear and remain to be investigated.