A new concept of neurologic manifestations of herniation of lumbar intervertebral disks has been presented in two preceding publications,1which clarify the clinical interpretation of this condition. The practical application of this knowledge is important in the general practice of medicine, and a brief review with additional information is herewith presented. Since the initial stimulating publication in 1934 by Mixter and Barr,2who demonstrated herniation of intervertebral disk by intraspinal injection of iodized oil and surgical exploration, there have been many contributions to the subject with increasing emphasis on the frequency of the lesion and localization by means of neurologic signs. There remained, however, lack of clear definition of the symptoms and signs of single nerve root compression by the common herniation of the nucleus pulposus of a lower lumbar disk. The symptoms caused by this herniation are those which in the past have been called "lumbago" and