The complaint of persistent low back pain in an athlete is usually related to an identifiable structural disorder. As with all other medical conditions, effective treatment relies on an accurate diagnosis. Certain sporting activities are associated with characteristic acquired lesions; this knowledge, when combined with a thorough history and physical examination, will often dictate when the clinician should refer an athlete for further testing. Most causes of back pain in athletes can be treated nonsurgically if they are identified early and treated appropriately. The common congenital abnormalities, acquired conditions, and overuse syndromes causing low back pain in athletes will be discussed, along with appropriate diagnostic tests and treatment regimens.