Behçet's disease is a systemic disease primarily affecting the eye, genital, and oral mucosa but is known to have various rare complications. A patient with a twenty-year history of Behçet's disease was admitted owing to dyspnea caused by massive chylothorax. Administration of corticosteroid, heparin, and urokinase was ineffective, but the thoracic fluid was well controlled by pleuropexy with Broncasma Berna. Chylothorax complicating Behçet's disease is extremely rare, having been reported in only 2 cases.