Liposarcoma is a malignant tumor that has an embryologic origin from mesodermal tissue depending on fatty tissue. Although liposarcoma is only 0.1% of all human neoplasms, it is the most common histology subtype of retroperitoneal soft tissue sarcomas. This tumor grows slowly. Diffuse abdominal pain is its most frequent symptom and abdominal mass is the most common sign. Aggressive surgical treatment is basic to get a complete resection and a local disease control. This objective is difficult because of the large tumor size it gets in the retroperitoneal location and the multiorgan involvement that require the resection of a high percentage of contiguous organs. We report a case of a giant retroperitoneal liposarcoma presenting like continuous left hemiabdominal pain because of the visceral compression. The right kidney was involved and suffering from renal vessel enlargement without renal function. There is a high probability of microscopic residual disease and a good follow-up of the patients is necessary as well as an adjuvant radiation therapy in some cases.