A 54-year-old man with chronic idiopathic myelofibrosis (CIMF) underwent RIST. His clinical course had been uneventful until day 60, when splenomegaly reappeared. Hepatic dysfunction developed on day 75. Recipient-type hematopoiesis increased to 51% on day 90. After rapid tapering of cyclosporin, serum levels of AST and ALP normalized in parallel with recovery of complete chimerism on day 134. Yet, jaundice progressed. He died of liver failure on day 176. Postmortem examination revealed neither GVHD nor VOD. Graft rejection following RIST for CIMF may lead to fatal hepatic damage through extramedullary hematopoiesis in the liver or cytokine-mediated immune dysregulations.