Langerhans-cell histiocytosis (LCH) is a rare condition with a wide clinical spectrum and variable prognosis. Patients with multisystem LCH have been treated with a variety of agents but may develop resistant and progressive disease. Based on a preliminary encouraging report on the activity of 2 chlorodoxyadenosine in this disease, we administered this agent to a patient with LCH which was resistant to corticosteroids and etoposide. After 4 courses of treatment the patient achieved a complete remission which is currently ongoing for 12 months. 2 CdA appears to be effective in patients with resistant LCH and warrants investigation in previously untreated patients with poor risk disease.