The effectiveness of decompressive surgery for lumbar spinal stenosis was assessed. A total of 94 patients were randomized into a surgical or nonoperative treatment group. At the 2-year follow-up, the mean differences in favor of surgery were: 7.8 in Oswestry disability index (scale, 0–100), 1.5 in leg pain (scale 0–10), and 2.1 in back pain. Walking ability, either reported or measured, did not differ between the two treatment groups. The results indicate a favorable effect of decompressive surgery both on leg and low back pain and on overall disability.