Allogeneic blood stem cell transplantation with reduced conditioning has been proposed as a new, potentially curative treatment option for patients with rheumatoid arthritis (RA). We report a 60-year-old woman with RA and coexisting multiple myeloma who was treated with high-dose melphalan and autologous blood stem cell transplantation (BSCT) followed by a nonmyeloablative allogeneic BSCT from her healthy dizygotic twin brother. She achieved a complete remission of her RA after autologous BSCT, but relapsed early despite complete donor chimerism following successful allogeneic transplantation with reduced intensity conditioning. This case illustrates that allogeneic BSCT following nonmyeloablative conditioning may be an uncertain option for curing patients with RA.