Pulmonary Langerhans cell histiocytosis (LCH) is an uncommon cause of interstitial lung disease. Corticosteroids and chemotherapeutic agents are frequently used to treat symptomatic patients but their efficacy is unclear. We describe a 66-year-old with biopsy-proven pulmonary and systemic LCH, whose pulmonary abnormalities responded dramatically to treatment with 2-chlorodeoxyadenosine (2-CdA). We propose that, in selected cases, 2-CdA should be considered in the management of pulmonary LCH.