Protrusion of intervertebral disks into the spinal canal is a subject that has been much discussed during the recent few years. 1 That it should assume a large place in our daily efforts to relieve pain and suffering is justified because of the frequency with which we are called on to treat intractable low back and pain, which often is an expression of protrusion of an intervertebral disk or disks in the lumbar region of the spinal column. The protrusion of a portion of one or more intervertebral fibrocartilages, with the consequent compression of the spinal cord or of one or more nerve roots, provides us with a real anatomic and pathologic explanation for the disability experienced by many patients. Such an explanation has been sorely needed. Too many patients have been treated, all too often unsuccessfully, for such incorrect and meaningless diagnoses as lumbosacral strain, sacro-iliac dislocation, sciatic