We report a 64-year-old woman treated with surgical intervention for late-onset chylothorax following a pleuropneumonectomy. The patient underwent an extrapleural pneumonectomy for diffuse malignant mesothelioma and was uneventfully discharged on postoperative day 29. Pleural effusion aspirated on postoperative day 9 was dark red. A chest roentgenogram taken at our outpatient clinic revealed a mediastinal shift on postoperative day 56. No bacterial infection was found in the milky effusion. We made a diagnosis of postoperative late-onset chylothorax based on the laboratory data obtained from tests of the pleural fluid. A repeat thoracotomy to ligate the lymphatic duct was performed because conservative management with chest tube drainage and no oral feeding was unsuccessful. The patient was discharged after the operation with a good clinical course.