We report a case of retroperitoneal chondrosarcoma in which preoperative radiological study induced to a possible diagnosis of sacral schwannoma. A 25-year-old woman was admitted to our neurosurgical institute for a progressive sciatic pain with gait difficulties with a sudden radicular deficit with right positive Lasegue's sign at 30 degrees, loss of Achilles reflex, sensory deficit on right S1 dermatome, and complete motor deficit of right plantar flexion. We performed an en bloc removal of the lesion via an anterior retroperitoneal approach. We believe that the treatment of choice is radical surgical excision of the tumor with complete en-bloc removal of the lesion; postoperative radiotherapy and chemotherapy should be valuated case by case.