Bone marrow transplantation (BMT) is currently the treatment of choice for patients with globoid cell leukodystrophy (GLD), particularly in the early phases of the disease. Elevated interleukin (IL)-6 levels in the central nervous system of the twitcher mouse, an animal model for GLD, have been held responsible for severe graft versus host disease (GVHD), and IL-6 knock-out mice have shown lower incidence of GVHD after BMT. Here we report an eight-year-old girl with late-onset advanced stage of GLD who developed severe GVHD and died following unrelated 5/6 matched cord blood transplantation. Serum IL-6 levels pre-BMT and at day +38 were elevated (20 pg/ml and 15 pg/ml, respectively). This observation may support the findings in twitcher mice suggesting a possible role for IL-6 in the pathogenesis of GVHD in transplanted patients with GLD.