Between 1990 and 1998, twenty-nine patients with neurological deficits after acute unstable fracture of thoraco-lumbar spine were treatment by surgery at National Taiwan University Hospital. An attempt was made to contact all patients but 4 patients were unavailable for evaluation. The remaining 25 patients were followed for an average of 47.9 months (range 24 to 108 months). Postoperative improvement was observed in 56% and 60% of patients in Frankel grade and muscle power respectively. No patient had any neurological deterioration after surgery. None of these patients with initial Frankel grade A and B regained their ambulatory ability. However, 15 patients (60%) with initial Frankel grade C and D became independent ambulators after surgery (P = 0.0046). None of these patients with initial grade 0 muscle power regained his ambulation ability but all 15 patients (60%) with initial grade 1 to 4 muscle power became independent ambulators after surgery (P = 0.113). 10 patients with initial Frankel A or B had an average 0.4 grade of improvement and 25 patients with initial Frankel C or D had an average 0.9 grade of improvement (P = 0.11). However, those 10 patients with initial power 0 had an average 0.2 grade of improvement and the other 25 patients with initial muscle power 1 to 4 had an average 1.5 grades of improvement (P = 0.003). According to this study, we conclude that Frankel grade and muscle power are good predictors for the clinical outcome of surgical treatment for unstable thoraco-lumbar spine fracture. Patients with such injuries should be managed aggressively especially when residual muscle power could be elicited after the period of spinal shock has passed.