A caucasian female infant with acute lymphoblastic leukaemia in second remission received a bone marrow transplantation. Engraftment was confirmed at 14 days following infusion of bone marrow from a sex-matched, ABO and HLA compatible sibling. 171 days posttransplantation the patient is clinically well and in haematological remission. A mild transient skin rash and hepatocellular disturbance, the only manifestations of graft versus host disease, responded successfully to high dose prednisone.