A 28-year-old woman was admitted to our hospital complaining of chest pain and dyspnea. Chest radiographs showed left pleural effusion. The effused fluid obtained by thoracocentesis was milky, and so chylothorax was diagnosed. A high-resolution chest CT (HRCT) scan demonstrated diffuse multiple cystic lesions, which were undetectable by conventional CT. An abdominal CT scan showed a retroperitoneal tumor. Since the effusion was resistant to conservative therapy, we performed clipping of the thoracic duct under the diaphragm. Since the effusion disappeared after continuous aspiration, 10 KE of OK-432 was administered into the pleural cavity, and the chylorrhea disappeared. The clinical diagnosis, based on the biopsy of the abdominal tumor, was lymphangioleiomyomatosis. Chylothorax developing from lymphangioleiomyomatosis is rare in Japan. However, we must consider the possibility of lymphangioleiomyomatosis in patients with chylothorax, and always perform chest HRCT.