We report a 24-year-old Japanese female hospitalized with jaundice and ascites. She exhibited hepatosplenomegaly, severe liver dysfunction, and slight polycythemia with an increase in serum levels of beta-thromboglobin and platelet factor 4. Bone marrow was hypercellular with an increase in progenitor cells. The aggregation response of platelets to ADP and to collagen was markedly increased. Venography revealed narrowed hepatic veins with "spider web' sign. Liver biopsy revealed hepatic congestion. Budd-Chiari syndrome was diagnosed, and was thought to be due to thrombosis related to myeloproliferative disorder. Liver transplant was successful in relieving symptoms.