A 35-year-old man stopped breathing after injecting a large dose of heroin. He subsequently received cardiopulmonary resuscitation from friends. He arrived to accident and emergency department with Glasgow Coma Scale of 13. On examination, he had distended and tense abdomen. CT Thorax, Abdomen, and Pelvis confirmed massive tension pneumoperitoneum. A 14 Fr intravenous cannula was inserted through the umbilicus to relieve the intra-abdominal pressure. An emergency laparotomy showed petechia along the anterior gastric wall, haematoma of lesser omentum but showed no evidence of gastrointestinal perforation or organ injury. Air leak test performed by insufflating air into the stomach via nasogastric tube and abdomen filled with normal saline showed no leak. On-table oesophagogastroduodenoscopy showed mild oesophagitis and petechia of cardiac gastric mucosa. He was treated with intravenous antibiotics and discharged on the fifth postoperative day with adequate analgesia.