A retrospective review of 603 cases of intradural benign tumors of the cauda equina are presented (283 schwannomas and 320 ependymomas). For each tumor, the clinical course and long-term postoperative results were analyzed: it emerged that differential diagnosis between neurinomas and non tumoral lesions is not possible if based on clinical findings alone and that neuroradiological diagnosis is more accurate when MRI is employed. Long-term prognosis of neurinomas was always favourable, while in the ependymomas, early diagnosis gives excellent results because prognosis is apparently directly correlated to the length of preoperative clinical history.