Spondylolysis and spondylolisthesis are not uncommon causes of low back pain and sciatica among the general population. Symptoms from these complaints also appear to be increasing in frequency among those who participate in competitive sports, especially those resulting in heavy pressures on the lumbar spine. Neural arch dysplasia is often a predisposing factor and there is evidence that genetic factors may play a role. Isthmic spondylolysis and mild spondylolisthesis not exceeding 10 mm can be satisfactorily cured by a simple operation involving screwing of the defect. Younger patients have better results and the operation permits the patient to withstand double loading on the lumbar spine so that most can return to work, including heavy manual labour, and to their previous sporting activities.