AbstractChylolymphatic cysts are an extremely rare variant of mesenteric cysts and account for 7.3% of all abdominal cysts. They can develop anywhere along the mesentery of the gastrointestinal tract and present in a wide range of symptoms. A 46-year-old male presented with mild abdominal pain and intermittent claudication in his right leg for the last 2 months and a history of a retroperitoneal resection of a simple abdominal cyst 5 years ago. Abdominal ultrasound and computerized tomography showed a fluid-filled cystic lesion measuring 17 × 11 × 10 cm in the right retroperitoneum. The cyst was surgically excised, and the histopathological examination was consistent with the chylolymphatic cyst. On a 1-year follow-up, the patient is recovered with no recurrence observed. Our report presents a case of a giant retroperitoneal chylolymphatic cyst with uncommon presenting symptoms and a rare etiology.