Nasogastric tube insertion is a common clinical procedure in medical care. However, misplacement of a nasogastric tube can cause unexpected complications which may even be life threatening in some cases. Herein, we describe a 43-year-old man who was admitted to the intensive care unit (ICU) via our emergency department, with the diagnosis of left-side empyema with acute respiratory failure. An endotracheal tube was inserted for mechanical ventilation, and then a nasogastric tube was inserted for decompression. A repeat chest radiograph 3 days later detected the misplacement of the nasogastric tube in the right main bronchus. The misplacement occurred even with the presence of an endotracheal tube with cuff inflation, as well as after confirmation of positioning by auscultation. Therefore, we emphasize the use of routine chest radiography confirmation of nasogastric tube positioning, in addition to conventional methods of auscultation, especially in patients in critical condition or with an existing endotracheal tube and mechanical ventilation.