BACKGROUND Soft tissue sarcomas are rare and account for less than 1% of all newly diagnosed malignancies. One-third of malignant tumors arising in the retroperitoneum are sarcomas. Liposarcoma is the most common soft tissue sarcoma and retroperitoneal sarcoma. Liposarcoma accounts for at least 20% of all sarcomas in adults and up to 41% of all retroperitoneal sarcomas. Here we present the case of a huge retroperitoneal liposarcoma and a brief literature review. METHODS A 34-year-old woman was referred to our hospital from a local clinic, because of abdominal distention, pain, and palpable mass. On admission we found that her abdomen was markedly distended. Computed tomography showed a the huge left ovarian mass that occupied almost the entire abdominal cavity. The mass consisted mainly of fat, and calcified material. She was operated under the diagnosis of a huge teratoma. The tumor was located in the retroperitoneal cavity and it abutted the left adnexa. The retroperitoneal tumor, including the left adnexa was removed. The tumor measured 22 x 15 x 11 cm, and showed many histological and pathological findings. On the basis of the histopathological finding, the tumor was diagnosed as a dedifferentiated liposarcoma of the retroperitoneum. The patient is presently undergoing radiation therapy. CONCLUSIONS In retroperitoneal liposarcoma, histological subtype, incomplete resection, contiguous organ resection, and older age are strongly associated with tumor-related mortality. For liposarcoma, it is necessary to customize the treatment strategy on a case-by-case basis.