Dr. M. J. Smyth was an orthopedic surgeon at St. James's Hospital, Leeds, and Dr. V. Wright a rheumatologist at the General Infirmary at Leeds, when they did the classic work reprinted in this paper. After that Dr. Smyth went to work in Canada and Dr. Wright has become Professor Rheumatology at the University of Leeds, with particular interests in the biomechanics of joints, seronegative polyarthritis and educational aspects of rheumatology. At the time when their paper first appeared in the Journal of Bone and Joint Surgery, there was good circumstantial evidence for relating sciatica to a protruded intervertebral disk impinging on the nerve, but little direct evidence. Further work on the sensitivity of structures in the spine has been done since these studies, particularly showing the innervation of the anterior aspect of the theca, but the basic thesis has stood the text of time. M. J. S.