We report a case of cerebral hemorrhage associated with cyclosporin A (CsA)/FK506-related encephalopathy that developed in a 16-year-old woman after allogeneic bone marrow transplantation. Hematopoietic engraftment occurred on day 15, and the patient developed systemic convulsions after CsA was replaced by FK506 for the treatment of acute graft-versus-host disease (GVHD). Based on magnetic resonance imaging, laboratory findings and cerebrospinal fluid studies, she was diagnosed as having CsA/FK506-related encephalopathy with cerebral hemorrhagic infarction. Although she recovered completely after discontinuation of FK506, she developed convulsions again 15 days after re-administration of FK506. A computed tomography scan showed cerebral hemorrhage. She died of respiratory failure. Vascular damage induced by immunosuppressive drugs and enhanced by acute GVHD seemed to be the cause of the cerebral hemorrhage. Since hypertension, which was present during both of the central nervous system events, seemed to have contributed to the development of the cerebral hemorrhage, it is proposed that CsA and FK506 should be reduced or discontinued when patients who have risk factors of hypertension become hypertensive even if they have no symptoms of neurotoxicity.