An 81-year-old female patient was admitted to the emergency room of our hospital with complaints of respiratory distress, abdominal ache, nausea, and intermittent vomiting. A plain X-ray of the abdomen and chest revealed air-fluid levels on the abdomen and the right side of the chest. Laboratory tests showed severe acidemia with a blood base excess level of -24.9 mmol/L. Since the patient was considered to have acute intestinal obstruction due to transverse colon herniation into the thorax through a foramen of Morgagni, emergency surgery was performed. Operative findings revealed that the retrosternal diaphragm had a defect of 5 cm in diameter and 20 cm in length with the transverse colon herniated into the thorax. The diaphragm defect was sutured first, and partial resection of the transverse colon was performed. After the operation, the patient had no symptoms and no recurrence has been observed during the 1-year follow-up. There have been 263 reported cases of Morgagani hernia in Japan. The case of the Morgagni hernia is reported here with some bibliographical comments.