Chylous ascites is rare. Etiology can be traumatic, atraumatic or idiopathic. We present a case of idiopathic peritonitis managed by laparoscopic drainage and a medium-chain triglyceride diet. We present a case of a 60-year-old white female who presented to the emergency department with diffused abdominal pain, migrated from the back, and clinical signs of peritonitis. Blood works showed high leukocytosis, and computed tomography showed a large amount of intraperitoneal and retroperitoneal fluid. During an emergency laparoscopy, a chylous ascites was seen and drained, but a causing factor was not identified intraoperatively. Postoperatively, medium-chain triglyceride diet was initiated for a period of 6 weeks, cytological, microbiological and chemical analysis showed elevated levels of triglycerides in absence of other disease. Multiple diagnostic tests revealed no malignancy nor another underlying pathological processes. patient recovered well with no complications. When confronted with chylous ascites, surgeons should drain the abdomen and do thorough evaluation. When no cause is found intraoperatively, surgeons should not take aggressive measures but instead initiate a medium-chain triglyceride diet and search for underlying causes by means of further laboratory testing and positron emission tomography combined with computed tomography (PET-CT). When no etiology is found, medium-chain triglyceride diet can be stopped with no reports of recurrence.