Abstract: Objective To study the clinical efficacy of combined DEVEX-cage and pedicle screw fixation for lumbar degenerative instability. Methods Twenty-three patients with lumbar degenerative instability（10 males,13 females） at the age of 39-68 years（mean 46.6 years） were treated with combined DEVEX-cage and pedicle screw fixation from November 2007 to December 2009.Preoperative lumbar dynamic X-ray showed lumbar degenerative instability at L3-4 in 1 patient,at L4-5 in 11 patients,at L5-S1 in 8 patients,and at L4-5/L5-S1 in 3 patients,respectively. Results The operation time was 1.5-2.3h（mean 1.8h）.The intra-operation blood loss was 150-260ml（mean 180.7ml）.No injury of dural matter,cerebrospinal fluid leakage,and nerve system occurred.The patients were followed up for 13 months-4 years（mean 3.2 years）.The ODI score was 41.37±3.68 before operation,11.25±2.21 one week after operation,9.98±2.08 three months after operation,and 9.06±2.68 at the final follow-up time after operation.The mean ODI score was significantly lower 1 and 3 months after operation and at the final follow-up time after operation than before operation（P＜0.01）.Good bony union was achieved in 22 patients and possible bony union was achieved in 2 patients.Mild 1eg pain developed in 2 patients after operation,which was improved after conservative treatment. Conclusion Combined DEVEX-cage and pedicle screw fixation is a good procedure for lumbar degenerative instability with a mild injury,a high safety and a good short-term effect.