A 16-Year-old boy with lymphoblastic lymphoma underwent an autologous bone marrow transplantation (ABMT) after conditioning with high-dose busulfan and cyclophosphamide. On day 39 post-transplant, right upper quadrant pain occurred with an increase in the size of the liver. Liver function tests showed a subsequent deterioration. Ultrasonographic studies of the abdomen disclosed hepatosplenomegaly, ascites, thickening of the gall bladder wall and a failure to visualize the major hepatic veins. The venocclusive disease of the liver (VOD) diagnosis was confirmed from these findings. Ultrasonographic monitoring reflected the disease status well and demonstrated a complete recovery from the VOD. We emphasize, thus, that abdominal ultrasonography can be applied easily, being a non-invasive procedure, and is useful in diagnosing VOD. Furthermore, the procedure can be repeated serially for evaluating the severity of VOD. Although engraftment was confirmed with granulocytes exceeding 500/microliters, platelet recovery was delayed; the megakaryocytes had not decreased in bone marrow aspirates and platelet-associated IgG was significantly elevated. Since autoimmune thrombocytopenia was highly suspected, to prevent immunosuppression danazol was given as an immune modulator instead of prednisolone, and a complete recovery was obtained. Accordingly, danazol can be used as an alternative to prednisolone for the treatment of autoimmune thrombocytopenia after bone marrow transplantation.