AbstractChylous leakage is a rare but serious postoperative complication of neck dissection (ND). Most chylous leakages are successfully treated either by drainage or ligation of the thoracic duct, but the resolution is occasionally prolonged. OK432 sclerotherapy is used to treat various refractory cystic diseases of the head and neck. Three patients were treated with OK432 sclerotherapy for refractory chylous leakage following ND. Case 1 involved a 77-year-old man with chylous leakage after a total laryngectomy and bilateral ND. Case 2 involved a 71-year-old woman who underwent total thyroidectomy and left ND for thyroid cancer. Case 3 involved a 61-year-old woman who underwent right ND for oropharyngeal cancer. In all patients, chylous leakage rapidly improved after OK432 injection without any complications. Our results suggest the efficacy of OK432 sclerotherapy in patients with refractory chylous leakage after ND.