A 60-year-old man was admitted to our hospital with a right inguinal swelling that had been growing in size without any pain for 7 months. We diagnosed the growth as a right inguinal hernia and operated on him. The growth, however, was found to be a tumor it situated along the spermatic cord and testicular vessels. We diagnosed it as a lipoma. The tumor was resected near part of the internal inguinal ring. Histopathological diagnosis showed well-differentiated liposarcoma of the sclerosing type. Postoperative computed tomography (CT) revealed a large residual tumor in the retroperitoneum. We believed that the tumor was a retroperitoneal liposarcoma and that it developed in the inguinal region. The residue of the liposarcoma was resected onto the right inguinal tract. A periodic follow up has been performed and no evidence of recurrence or metastasis has been seen in the 4 years and 9 months since the second surgery. No adjuvant therapy was performed. Inguinal liposarcomas are relatively rare and in most cases these tumors are thought to originate in the spermatic cord. The origin of the tumor is believed to be the retroperitoneum.