We describe an operative approach to lumbar canal stenosis which, unlike laminectomy, takes into account the segmental pathology of the disease. At each level involved, a bilateral subarticular fenestration is performed under high magnification. The medial third of each facet joint is first removed with an air-powered drill; then the remaining two-thirds of the joint is undercut with the drill to allow a generous fenestration in the thickened ligamentum flavum and adjacent laminae. All tissue responsible for neural compression is removed, but the spinous processes, interspinous ligaments, and much of the facet joints and laminae are preserved. Spinal stability is maintained and, because tissue disruption is minimized, postoperative discomfort is usually reduced, promoting early mobility and reduced hospital stay. The operation is described in detail, and the results of operation in 32 patients are assessed. The follow-up periods now range from 17 to 58 months. Of 23 patients who presented with neurogenic claudication, 14 (61%) obtained complete relief and 7 (30%) improved significantly. The mean hospital stay was 9 days (range, 4 to 17 days).