Langerhans cell histiocytosis (LCH) embraces disorders characterized by the presence of marrow-derived abnormal Langerhans cells. A small number of patients with multisystem disease, vital organ dysfunction and rapid disease progression are considered to have a poor prognosis despite various treatments. Antiproliferative and immunosuppressive therapy, in combination with marrow transplantation, could be the appropriate treatment for these poor-prognostic patients. Four patients with progressive LCH were treated with high dose chemotherapy and fractionated total body irradiation followed by either an allogeneic (n = 2) or autologous (n = 2) marrow graft. Two of them are alive and have been disease free for almost 2 and 4 years after marrow grafting, respectively. One of the two survivors is the recipient of an allogeneic and the other of an autologous marrow graft. Two patients died, one of intrapulmonary hemorrhage 14 days after transplantation with active disease at autopsy, and the other of relapse of the original disease 355 days after marrow grafting. For patients with multisystem progressive LCH, allogeneic and autologous marrow transplantation may offer an opportunity for long-term remission and disease-free survival.