STUDY DESIGN: We have studied prospectively the clinical and radiological results after unilateral pedicle screw fixation in degenerative lumbar spinal stenosis. OBJECTIVE: To evaluate the clinical significance of unilateral pedicle screw fixation. SUMMARY OF LITERATURE REVIEW: The use of pedicle screw fixation has significantly increased fusion rate in degenerative lumbar spinal surgery. However, the rigid spinal fixation may result in deterioration of the juxta-fusion segments and lead to the stress-shielding of vertebral bodies within the stabilized segments. MATERIALS AND METHODS: From July 1997 to October 1998, we had performed bilateral posterolateral fusion and unilateral pedicle screw fixation for degenerative spinal stenosis in nign cases. The main indications for unilateral pedicle screw fixation included patients undergoing decompressive laminectomies, which preserved the facet joints. One of the patients was initially scheduled for bilateral pedicle screw fixation. However, during the application of the instrumentation, loosening of a pedicle screw was occurred. Only unilateral pedicle screw fixation on the contralateral side was kept. The clinical results were assessed the back pain, radiating pain and claudicaion. We assessed the radiologic results such as fusion status and maintenance of disc height. RESULTS: The back pains were improved in 6 cases , and the radiating pain and claudication were improved in eight cases after the operation. According to Lenke's grade, fusion status were showed grade A in nign segments and grade B in four segments at the last follow-up radiograph. The loss of disc height averaged 7.8(1-25)% in thirteen segments. CONCLUSION: Unilateral pedicle screw fixation is one of the useful methods for patients undergoing decompressive laminec-tomies, which preserve the facet joints in degenerative lumbar spinal stenosis.