An 83-year-old woman was admitted to our hospital because of fever and disturbance of consciousness. Pneumonia and multiple organ failure were diagnosed from symptoms, a chest X-ray film, and laboratory findings. With the administration of antibiotics and an antiprotease inhibitor, the pneumonia and multiple organ failure began to resolve, but consciousness remained disturbed. A nasogastric feeding tube was inserted to provide parenteral nutrition. Neither abnormal resistance nor reflex coughing were noted during insertion. Bubbling rales were not heard on auscultation, and a chest X-ray film revealed that the tube had traversed the right bronchial tree, perforated the lung, coiled up in the right pleural vavity, and caused a right pneumothorax. The tube was immediately removed. The pneumothorax was treated with an intercostal drainage tube for 1 day and resolved without further problems. This case shows one of the dangers involved in inserting nasogastric feeding tubes. The medical community should be aware that pulmonary complications may develop after such tubes are inserted in patients with risk factors.