Objective: Whether or not emergent decompression/fusion surgery for paralysis caused by metastatic spinal tumors of unknown origin improves patient neurological outcome and survival remains unclear. This study aimed to evaluate the clinical outcomes of emergent decompression/fusion surgery for paralysis caused by spinal tumors of unknown or not previously diagnosed origin.Patients and Methods: Data from the medical records of 11 patients with spinal tumors of unknown origin (study group) were compared with those of 15 patients with metastatic spinal tumors of known origin (control group). The outcome measures were postoperative performance status, motor function evaluated with the Frankel grade, and actual survival after surgery as compared with the estimated survival calculated using the Tokuhashi score. χ2 analyses were performed to evaluate differences between the groups.Results: The mean performance status was 3.6 preoperatively, which improved to 2.9 postoperatively (P<0.05), in the unknown origin group and 3.6 preoperatively, which improved to 2.7 postoperatively (P<0.05), in the control group. Seven patients (64%) in the unknown origin group showed improvement in paralysis by ≥1 Frankel grade. By contrast, only 4 patients (27%) in the control group showed improvement in paralysis. The unknown origin group tended to show better improvement (P=0.05). All the patients in the unknown origin group underwent adjuvant therapy after definitive diagnosis following surgery. The unknown origin group showed a slight tendency toward better survival than toward the estimated survival.Conclusion: Emergent decompression/fusion surgery for patients with paralysis caused by metastatic tumors of unknown origin is potentially useful for diagnosing tumor origin and improving neurological outcomes and performance status, and thus for extending survival.