PURPOSE: Langerhans cell histiocytosis (LCH) has a wide spectrum of clinical features. Especially, disseminated disease has been associated with a chronic course, high rate of morbidity and possible mortality. The purpose of our study was to investigate the clinical features, subsequent disease course, survival and late sequelae in multisystem LCH (ms-LCH). METHODS: Fourteen cases diagnosed to histologically proven ms-LCH at Pusan National University Hospital between January 1991 and December 1997 were enrolled in this study. All patients received combination chemotherpy. The medical records were retrospectively reviewed for organ involvement at diagosis, disease course, and late sequelae. RESULTS: 1) The peak incidence was between 6 months and 2 years and sex distribution revealed female predominance with the ratio of 1.8:1. 2) Mean number of involved organs was 4.4 and the most frequently involved organ was liver (85.7%) followed by bone, middle ear, skin and spleen. 3) The mean duration of follow up was 41.6 27.5 months. And the overall estimated survival rate at 5 years was 75.9%, with an estimated disease free survival rate of only 40.8% at 5 years. 4) Three patients died and the causes of death were respiratory failure due to pneumonia, gastrointestinal bleeding due to hepatic failure and septicemia. 5) Late sequelae were seen in 42.8% among 14 patients. The most common sequelae were skeletal defects in 21.4% and diabetes insipidus in 21.4%. 6) Among the late sequelae, 3 patients had vertebra plana. Conservative treatment was done and long term follow up of 28.7 7.0 months demonstrated partial healing of the vertebra plana in two cases and no improvement in one. 7) The diabetes insipidus developed in 3 cases, at diagnosis, at 14 months and 20 months after diagnosis respectively. None of the cases received radiation therapy. All of them responded to anti-diuretic CONCLUSION: These data show that, despite the favorable survival, about half of ms-LCH patients had further dissemination of disease or late sequelae. Further treatment needs to be designed to prevent disease progression and late sequelae. hormone replacement therapy.