One of the most frequent and incapacitating medical and social problems of our times is back pain. In most patients the cause of the symptoms remains unknown, although some relevant clues have been discovered over the last few years: mechanical, nutritional, chemical, social, psychological and genetic factors. Pathoanatomic conditions that are generally accepted as related to the symptoms include disc herniation, fracture, infection, spinal stenosis, spondylarthropathy and spondylolisthesis. Diagnostic problems will only be solved by considering and synthesis of all findings.