BACKGROUND: Cardiac herniation, especially right-sided herniation, is a fatal complication which causes sudden hypotension due to obstruction of the vena cava. Here, we describe a case of cardiac herniation identified without any symptoms after right extrapleural pneumonectomy performed for diffuse pleural mesothelioma. CASE PRESENTATION: A 72-year-old man with diffuse pleural mesothelioma underwent a right extrapleural pneumonectomy after chemotherapy. The tumor had widely invaded the pericardium, necessitating pericardial resection. The pericardial defect was approximately 10 × 6 cm and was reconstructed with a 0.1-mm polytetrafluoroethylene sheet. Routine chest radiographs taken just after the operation were normal. A chest radiograph on postoperative day one revealed cardiac herniation but he remained hemodynamically stable. An urgent re-thoracotomy was performed for pericardial reconstruction. Severe hypotension occurred immediately before the operation, but was improved upon placing the patient in the left lateral decubitus position. Postoperatively, he developed postoperative complications including chylothorax and empyema, and was discharged 118 days after surgery. CONCLUSIONS: Cardiac herniation can occur without any symptoms following right pneumonectomy with pericardiectomy. Urgent reoperation is warranted due to the high risk of impending shock, even in hemodynamically stable patients.