OBJECT Standard treatment options for patients with lumbar spinal stenosis include nonoperative therapies as well as decompressive laminectomy. The introduction of interspinous decompression devices such as the X-STOP has broadened treatment options, but data comparing these treatment strategies are lacking. The object of this study was to provide a cost-effectiveness analysis of laminectomy, interspinous decompression, and nonoperative treatment for patients with lumbar stenosis. METHODS The authors performed a structured literature review of lumbar stenosis and constructed a cost-effectiveness model. Using conservative treatment, decompressive laminectomy, and placement of X-STOP as the treatment arms, their primary analysis evaluated the optimal treatment strategy for a patient with lumbar stenosis at a 2-year time horizon. Secondary analyses were done to compare cases in which patients required single-level procedures with those in which multilevel procedures were required as well as to examine the outcomes for a 4-year time horizon. Outcomes were calculated using quality-adjusted life years and costs were considered from the perspective of society. RESULTS Laminectomy was found to be the most effective treatment strategy, followed by X-STOP and then conservative treatment at a 2-year time horizon. Both surgical procedures were more costly than conservative treatment. Because laminectomy was both more effective and less costly than X-STOP, it is said to dominate overall. When single level procedures were considered alone, laminectomy was more effective but also more costly than X-STOP. CONCLUSIONS Lumbar laminectomy appears to be the most cost-effective treatment strategy for patients with symptomatic lumbar spinal stenosis.