Subcutaneous emphysema and pneumomediastinum may be caused by air leakage from an extra-pulmonary source. In this report, we described the case of a 63-year-old man who presented to our emergency department with severe abdominal pain and dyspnea. The chest radiograph showed subcutaneous emphysema, pneumomediastinum, and pneumoperitoneum, but no pneumothorax. An exploratory laparotomy revealed a perforated peptic ulcer at the anterior wall of the duodenum. The subcutaneous emphysema and pneumomediastinum resolved rapidly after the perforation was closed. We also reviewed the literature on this rare complication of peptic ulcer.