Purpose: When lymphatic pathways are disrupted via obstruction or traumatic injury, a temporary or chronic chyle leak may result, which is defined as the presence of chyle that collects outside of the lymphatic vessels within the thoracic or abdominal cavities. For a chyle leak that is refractory to surgical repair, no good options exist. Radiation therapy (RT) can result in scarring and fibrosis of the lymphatic fistula. We report on the first clinical case in the United States with the successful use of low-dose (LD) RT in the management of refractory chylous ascites. Methods and Materials: A 74-year-old man developed significant chylous ascites after a laparoscopic Nissen fundoplication. After failure of numerous conservative and surgical interventions, he was referred for radiation medicine. We delivered a dose of 10 Gy in daily 1 Gy fractions to the para-aortic region, including the cisterna chyli and thoracic duct from T12 to L2. Results: The patient tolerated LD-RT well with no toxicity. By the time of the 8-month post-RT follow-up visit, he had decreased chylous ascite levels and required no paracentesis or peritoneovenous shunting. There was no evidence of chylous ascites or recurrent chyle leak at the time of the 18-month follow-up visit. Conclusions: LD-RT for refractory postoperative chylous ascites is a safe and reasonable option that can provide temporary relief in addition to other conservative methods. This is the first reported case of refractory chylous ascites in the United States that was successfully treated with LD-RT.