Lumbar spinal stenosis may be defined as any type of narrowing of the spinal canal, nerve root canals or intervertebral foramina. It may be local, segmental or generalized and may be caused by the encroachment of bone or soft tissue. The narrowing may involve the bony canal alone or the dural sac or both. Routine conventional radiographs or sagittal tomographs cannot accurately assess the midsagittal diameters of the lumbar canal or detect encroachment on the canal by osteoarthritis articular facets. However, myelography and computed tomography provide a means for distinguishing between herniation of a disc and bony encroachment on the spinal cord. The goals of surgical treatment in lumbar spinal stenosis are the relief of pain and the preservation or restoration of neurological functi ions. The surgical strategy is based on the patients symptoms and roentgenographic findings. Eighty-two operative cases of lumbar spinal stenosis were analyzed who were admitted in the Department of Orthopedic Surgery at Yonsei University College of Medicine from January, 1979, to July, 1984. The male female ratio was 1.3:1 and 66 cases (80.5%) included in their 50's and 60's. The results of the study are as follows: 1. Clinical symptoms included aggravation of pain during back extension (28.0%); back pain with radiating pain (22.0%); paresthesia of extremities (18.3%); back pain only (13.4%); and claudication (12.2%). 2. On physical examination, the straight leg raising test showed positive results in 25.6%, motor changes occurred in 24.4%, sensory changes in 20.7%, and DTR changes in 11.0%. 3. The most frequent level of spinal stenosis, L5-Sl invertebral space, was found in 68.3%(56cases) followed by L4-L5 intervertebral space found in 61.0% (50 cases). 4. Operative findings induded 31 lesions (46.3%) identified as herniated or ruptured discs,20 lesions (29.9%) identified as thickening of lamina and ligamentum flavum, and 5 lesions (7.5%) as compression of a nerve root by scar adhesion. 5. Of the 67 patients (81.7%) operated through the posterior surgical approach, 52 cases (77.6%) were effective; and of the 15 patients operated on by the anterior surgical approach, 9 cases (60.0%) were effective. 6. When the duration of symptoms was less than 1 year and the involved level of spinal stenosis was less than 2, operative results were satisfactory. 7. When there was a degenerative type of stenosis without a herniated or ruptured disc, operative results were excellent. 8. For post operative external support, 32 cases (39.0%) wore body jacket cast and 38 cases (46.3%) wore back braces.