Acute herniation of the heart is an uncommon complication in patients undergoing pneumonectomy with associated pericardial resection. We report the case of a postoperative cardiac herniation after a right extrapleural pneumonectomy following neoadjuvant chemotherapy for malignant pleural mesothelioma. After surgery the patient was completely asymptomatic, but a postoperative chest X-ray revealed unexpected massive dextrocardia. The patient was immediately brought back to the operating room: a cardiac herniation was found to be caused by a partial dehiscence of the pericardial prosthesis suture. The defect was repaired without consequences.