A retroperitoneal liposarcoma that marginally involved the right kidney and ovary was presented clinically as an adnexial mass in a 61-year-old woman. At laparatomy a large retroperitoneal mass in addition to the right kidney and ovary was removed totally. A well-differentiated retroperitoneal liposarcoma was detected in histological speciment. Adjuvant irradiation was given. The 5-year survival rate of retroperitoneal liposarcoma is low. Curative resection remains the main treatment for primary and recurrent liposarcomas.