Spondylolysis is most commonly observed in the lumbar spine, particularly L5, and is associated with spondylolisthesis, or anterior "slippage" of a vertebra in relation to an adjacent vertebra. Isthmic spondylolisthesis is the result of a pars interarticularis defect and will be the only type of spondylolisthesis addressed in this review. Conclusions: Spondylolysis and spondylolisthesis represent a relatively common cause of low back pain, especially in young athletes, and a less common cause of neurologic compromise. When discovered in a symptomatic patient with corroborating imaging findings, early intervention provides an excellent prognosis. Herein, we review the anatomy and pathology of spondylosis and spondylolisthesis of the L5 vertebra. © 2012 Springer-Verlag Berlin Heidelberg.