Mestastatic tumors of the spine often cause severe pain and paralysis because of deformity and neural encroachment. As oncology now extends the life expectancies of these patients, spinal decompression and stabilization is necessary. We consider that prophylactic stabilization of the spine is analogous to prophylactic nailing of a femur with a pathologic lesion. Both the femur and spine are weight-bearing structures. The advent of segmental instrumentation makes this a feasible accomplishment with minimal morbidity. Seventeen patients with metastatic disease of the spine at Rush-Presbyterian-St. Luke's Medical Center, Chicago, were reviewed. All maintained spinal stability postoperatively. Eleven of the 17 had significant pain relief for 3 months or more. Five of 11 paralyzed patients had significant neural recovery. A classification for treatment purposes regardless of tissue type was developed. Once classified, the surgical goals for these patients were to decrease pain, to preserve or to improve neurologic function and to mobilize the patient without external orthosis.