One hundred forty-two patients with the common types of spinal stenosis were treated by posterior lumbar interbody fusion (PLIF). The majority of the patients had one or more decompressive procedures prior to PLIF. The results were excellent or good in 78%. A review of the literature concerning long-term results of decompressive procedures indicates a short-term failure rate of 15%-20% and about 50% failure by ten or more years after the operation. Anterior fusion in primary disc lesions produces admirable results but is of little value in spinal stenosis. Long-term reports of the success rates of posterior lumbar interbody fusion indicate that this operation combines the success rate of an anterior interbody fusion with the benefits of posterior decompression.