We report a 12-year-old boy with primary bronchopulmonary fibrosarcoma (PBPF). He was misdiagnosed a having asthma until he presented with acute respiratory distress syndrome. Chest x-ray showed atelectasis of the right lung. Bronchoscopy performed to rule out foreign body inhalation revealed a friable mass obstructing the right main bronchus. Successful treatment was achieved with surgical resection of the lesion followed by radiotherapy and chemotherapy. (C) 2004 Wiley-Liss, Inc.