The defect in the pars interarticularis of spondylolisthesis may be dependent on contributing factors relatedto trauma and stress to which the neural arch is subjected, superimposed on a hereditary diasthesis. Posteriorwedging of 5th lumber vertebral body in lumbosacral spondylolisthesis together with the degree of slip have been measured. The average wedging in spondylolisthesis is singnificantly greater than patient without this condition, and forms a characteristic radiological sign. The degree of wedging and slip show a statistically validcorrelation. The diagnosis of spondylolisthesis is becomming more prevalent as the complelxity of our societyresult in the increasing use of roentgenography of the lumbar spine. Isolated lateral deviation and rotation of spinous process seen in anteroposterior radiographs of the lumbar spine seems to be associated with pathology inthe pars interarticularis.