Schwannomas are benign neurogenic soft tissue tumors arising from the Schwann cells which are sheath cells of peripheral nerves. Retroperitoneal schwannomas are very rare. The are not usually recognized until they cause symptoms from mass effect, and thus, they may reach very large size. In this paper, we report a 60-year-old female patient who was admitted to our hospital with a complaint of abdominal discomfort. Preoperative computed tomography of the abdomen detected a giant retroperitoneal mass. The tumor was totally resected with a prediagnosis of retroperitoneal schwannoma based on computed tomography findings without using additional imaging methods or biopsy. The patient was discharged without any complication on the 4th postoperative day. Correlative findings of preoperative radiological and postoperative histopathological examinations of retroperitoneal schwannoma are discussed in detail.