Transfer of donor immunity has been demonstrated in animal models of both allogeneic and syngeneic bone marrow transplantation (BMT). Clinical case reports have suggested that human autoimmune disease may be similarly transferred. However, it is difficult to completely exclude autoimmune phenomena associated with graft-versus-host disease (GVHD) as previously reported cases are of allogeneic BMT. In addition, the onset of autoimmunity has been distantly related to the timing of the transplant, perhaps because of the immunosuppression used for prophylaxis and treatment of GVHD. We describe a patient in whom the development of psoriasis shortly after receiving syngeneic bone marrow from a psoriatic donor and its recurrence with arthropathy following a second syngeneic BMT provide more direct evidence for the adoptive transfer of human autoimmune disease, probably by T cells.