When surgically removing a spinal nerve schwannoma, preservation of the involved root is attempted and may be feasible. However, in large tumors, sacrifice of the nerve root is often required to achieve total removal of the tumor, and the resection does not always result in postoperative neurological deficit. The present study was designed to determine the incidence and extent of neurological deficit as correlated with resection of the root, performed between 1976 and 1987 in 86 cases at the time of total removal of spinal schwannoma. Thirty-one patients underwent sacrifice of a root critical for the function of the upper (C5-T1, 14 cases) or the lower extremities (L3-S1, 17 cases). This report is limited to these 31 cases. Only seven patients (23%) developed detachable motor or sensory deficits postoperatively. All deficits were no more than partial loss of strength or sensation. Fifteen of the 31 patients had large tumors with extradural components, which necessitated sacrifice of the entire motor and sensory radix; however, 11 (76%) of these 15 did not develop any deficits referrable to the involved myotome or dermatome. Six cases showed histological characteristics of "neurofibroma," with axons intermingled in the tumor, and none developed a postoperative deficit. Preoperative electromyography was performed in 23 cases. Of 13 patients with findings of denervation, five developed deficits after surgery; the other 10 patients showed no evidence of denervation, and none had deficits after surgery. These results indicate that the spinal roots giving origin to schwannoma are frequently nonfunctional at the time of surgery, and risks of causing disabling neurological deficit after sacrificing these roots are small.