There are few reports describing the association between antiphospholipid antibodies, including the lupus anticoagulant, and bone marrow or peripheral stem cell transplantation. Autoimmune syndromes and autoantibodies such as lupus anticoagulant and anticardiolipin antibodies have been described following allogeneic bone marrow or peripheral blood stem cell transplantation, particularly in patients who develop chronic graft-versus-host disease (GVHD). The association between Lupus anticoagulant and acute GVHD has not been previously described. We report a patient who developed a de novo lupus anticoagulant on day +34 after a matched-related allogeneic peripheral stem cell transplant. No clinical evidence of systemic thrombosis was observed and the lupus anticoagulant disappeared following immunosuppressive therapy with a combination of steroids and infliximab.