Chylous ascites is an uncommon complication seen in patients who have received radiotherapy to the abdomen. However, the morbidity caused by peritoneal ascites makes this an important complication to be considered when giving abdominal radiation to oncology patients We present the case of a 58-year-old woman with gastric adenocarcinoma, who consulted for recurrent ascites after receiving abdominal radiotherapy as an adjuvant treatment to surgery. Different tests were carried out to evaluate the cause. Malignant abdominal relapse and infection were ruled out. Paracentesis evidenced swallowed fluid, therefore, the possibility of chylous ascites due to radiotherapy was considered. Intrathoracic, abdominal, and pelvic lymphangiography was performed with Lipiodol and the absence of cisterna chyli was confirmed as the cause of refractory ascites. After the diagnosis, the patient went under aggressive in-hospital nutritional support treatment, with clinico-radiological response.