The case reported here is a 32-year-old man with a sudden onset of chest pain and an acute deterioration of lung function. An incarcerated Morgagni hernia was diagnosed with a computer tomographic CT scan, and repaired electively via a midline laparotomy. Morgagni hernia is a rare type of congenital diaphragmatic hernia, which may not be symptomatic until adulthood when the patient presents with acute symptoms or incarceration.