Disorders of the lumbar spine are among the most common medical problems in western countries, affecting up to 80% of people at some time during their lives. The epidemiology and impact of six specific disorders of the lumbar spine are reviewed. These include prolapsed discs, disc degeneration, osteoarthrosis of the apophyseal joints, fractures and dislocations of vertebrae, osteoporosis, and spondylolisthesis. Various mechanical factors contribute to the causation of most of these disorders, but other underlying pathologic mechanisms are important as well. In light of the great impact of these conditions on society and on individuals, it is concluded that there is a considerable need for a greater allocation of resources for improvement in methods of prevention, diagnosis, and treatment.