We describe the outcome of a 20-month-old female and a 6-year-old male, both of whom had acutely developed severe respiratory distress with tachypnea, cyanosis and, in Patient 2, thoracic pain. Chest X-ray and CT scan showed interstitial pulmonary involvement and a bullous process with bilateral pneumothoraces for both children. Pulmonary biopsy confirmed the diagnosis of Langerhans cell histiocytosis (LCH). Laboratory testing and skeletal radiography did not reveal any other involvement of LCH. The patients received chemotherapy (prednisone, vinblastine, 6-mercaptopurine). They had recurrent episodes of pneumothorax during follow-up and placement of chest tubes was the treatment chosen. They were asymptomatic, with regression of bullae and disappearance of pneumothorax at 58 and 63 months of follow-up, respectively. Pulmonary function tests done during follow-up were normal in both patients. Despite severe pulmonary involvement, conservative surgical treatment and moderate chemotherapy produced good results in these two rare cases. Pediatr Blood Cancer 2007;48:241–244. © 2006 Wiley-Liss, Inc.