Severe aplastic anemia (SAA) is a frequent complication of orthotopic liver transplantation for non-typeable viral hepatitis. Allogeneic bone marrow transplantation (BMT) may successfully reconstitute hematopoiesis but the optimal conditioning regimen and graft-versus-host disease (GVHD) prophylaxis in such patients are unknown. Allogeneic BMT was undertaken in an 8-year-old male patient who developed SAA 6 weeks after cadaveric orthotopic liver transplantation for fulminant hepatic failure secondary to presumed non-typeable viral hepatitis. The preparative regimen for his HLA genotypically identical sibling BMT consisted of cytoxan and anti-thymocyte globulin. Tacrolimus (FK506) and prednisone, used to prevent liver graft rejection, were supplemented with methotrexate on post-BMT days, 1, 3, 6 and 11 for GVHD prophylaxis. Engraftment proceeded promptly and without complications. Transfusion dependence resolved 6 weeks after BMT. The patient is alive and well 1 year after his BMT on FK506 and prednisone without any signs of GVHD or liver allograft rejection. This case is the first demonstration of the feasibility of continuing FK506 used for prevention of liver graft rejection as GVHD prophylaxis for allogeneic BMT.