Chyloascities is an extravasation of milky chyle into the peritoneal cavity due to tumor , inflammation or rarely postoperative lymphatic trauma.It is an unusual complication that can lead to significant immunologic and nutritional consequences.We experienced one case of chyloascites after aorto-bifemoral bypass graft in a patient with aorto-iliac occlusive disease.The patient was a 62-year-old male, who suffered from severe progressive claudication for 5 months. A 16$ imes$ 8mm gelsealed Dacron-Y shaped graft was used in arterial reconstruction. A bloody-milky fluid was drained through the operative wound from 3days after operation and evaluated biochemically.Diagnosis of chyloascites was made with repeated paracentesis and examination of the fluid.After Total parenteral nutrition[T.P.N] for 3 weeks from 6days after operation, chyloascites was controlled sufficiently and maintained a good graft-patency in abdominal sonogram.