Retroperitoneal Schwannama is relatively rare and benign tumor originating from Schwann cell. Schwannomas arising in the retroperitoneum are infrequently reported. The majority of Schwannoma is found incidentally and misdiagnosed for other benign conditions both clinically and radiologically. We report a case of a benign retroperitoneal pelvic Schwannoma which was preoperatively misdiagnosed as an ovarian tumor with brief review of literatures.