Abstract Background: Liquid nitrogen (LN) ingestion is unusual, but may be encountered by poison centers, emergency physicians, and general surgeons. Unique properties of LN produce a characteristic pattern of injury. Case Report: A 19-year-old male college student presented to the Emergency Department complaining of abdominal pain and “bloating” after drinking LN. His presentation vital signs were remarkable only for mild tachypnea and tachycardia. On physical examination, he had mild respiratory difficulty due to abdominal distention. His abdomen was tense and distended. Abdominal X-ray studies revealed a massive pneumoperitoneum. At laparotomy, he was found to have a large amount of peritoneal gas. No perforation was identified. After surgery, the patient made an uneventful recovery and was discharged 5 days later. At 2-week clinic follow-up, he was doing well without complications. Discussion: Nitrogen is a colorless, odorless gas at room temperature. Due to its low boiling point (−195°C), LN rapidly evaporates when in contact with body surface temperatures. Therefore, ingested LN causes damage by two mechanisms: rapid freezing injury upon mucosal contact and rapid volume expansion as nitrogen gas is formed. Patients who ingest LN may develop gastrointestinal perforation and massive pneumoperitoneum. Because rapid gas formation may allow large volumes to escape from tiny perforations, the exact site of perforation may never be identified. Conclusion: In cases of LN ingestion, mucosal injury and rapid gas formation can cause massive pneumoperitoneum. Although laparotomy is recommended for all patients with signs of perforation, the site of injury may never be identified.