Ninety patients with biopsy-proven Langerhans cell histiocytosis (LCH) were enrolled from June, 1983, to December, 1988, in the multicenter AIEOP-CNR-H.X. '83 study. They were divided into two groups: poor prognosis (PP), comprising 11 children with organ dysfunction (OD), and good prognosis (GP), made up of 79 patients without OD. Eighty-four patients were evaluable for treatment results. Among GP patients, 16 with a single lesion received only local treatment, while 59 entered a clinical trial of immunotherapy and/or monochemotherapy with vinblastine (VBL). Nonresponders, sequentially received doxorubicin (ADM) and then etoposide (VP16). PP patients were treated with 4 week cycles of vincristine, ADM, cyclophosphamide, and prednisone for nine courses. The overall survival was 92.8% (100% for GP patients and 45.5% for PP patients) at 48 months. The complete response (CR) rates for immunotherapy, VBL, ADM, and VP16 were 10%, 62.9%, 42.8%, and 88.2%, respectively. Two of the 11 PP patients had a CR (18.2%), while six died and three are still alive with recurrent disease. The overall incidence of disease-related disabilities was 47.7%, while that of diabetes insipidus was 20%. Monochemotherapy is probably adequate in GP patients, while more effective treatments are needed for PP patients.