A female patient with severe idiopathic aplastic anaemia received a successful bone-marrow transplant from her HLA-identical, mixed-lymphocyte-culture-compatible, brother. 8 months after transplantation she had localised cutaneous measles. Chronic sclerodermatous changes developed which were indistinguishable from chronic graft-versus-host disease and were limited to the areas of the original exanthem. Interaction between viral infection and minor histocompatibility differences probably resulted in graft-versus-host disease in this patient.