Graft-versus-host disease (GVHD) is most commonly seen as a complication of bone marrow transplantation, although it can occur whenever tissue or blood products are given whereby immunologically competent donor lymphocytes react against host tissues. A 65-year-old man with non-Hodgkin's lymphoma developed a severe widespread erosive eruption of the skin and mucosal surfaces. Clinically and histologically it was identical to cutaneous GVHD even though the patient had never received tissue or blood products. He failed to respond to conventional therapy for GVHD, but his skin improved significantly on treating his underlying lymphoma, which eventually proved fatal. There are two previous reports of GVHD associated with malignancy but we believe this to be the first case secondary to a lymphoma.