The incidence of the spondylolysis is very low before five years but during the adolescence the incidence increase. The etiologic factors of spondylolisthesis are congenital and acquired. The acquired factors are traumatic and stress fracture. Then there are many congenital properties of the etiologic factors for the spondylolisthesis because several congenital anomalies are combined with spondyolysis or isthmic spondylolisthesis. But there are few articles about relationship between the spondylolysis or isthmic spondylolisthesis and the congenital anomalies around the lumbosacral area. The purpose of this particular study is to search the etiologic factors that increase the degree of the vertebral slippage and relationship between the spondylolysis or ishtmic spondylolisthesis around the lumbosacral area. The plain X-ray and computed tomograms were taken in the 48 patients and the 26 control group that have not chronic low back pain previously. The patients were divided into three groups, such as the spondylolysis, grade I spondylolisthesis, and grade II spondylolisthesis. The parameters measured from the plain X-ray were the incidence of congenital anomalies and degree of vertebral slippate. The parameters measured from the computed tomograms were fact angles and the degree of pseudodisc. Tropism were present for 5 cases, and 16 cases at L3-4 facets, 12 cases, and 22 cases at L4-5 facets, 10 cases, and 28 cases at L5-S1 facets in control and patients group. There was no correlation between the presence or absence of tropism and the vertebral slippage. The sacralization was related with the vertebral slippage but other congenital anomalies were not related to the degree of vertebral slippage. There was a increment of vertebral slippage according to the increase of facet angle, but the linear correlation was absent on regression analysis. So statistical significance was absent among the control group and 3 patients groups. And the vertebral slippage was not significantly different among the groups that were divided according to the difference of facet angle. There was a linear correlation between the degree of the pseudodisc and the degree of vertebral slippage of square=0.60 on regression analysis. At present study, there was a trend of increase of vertebral slippage according to increase of facet angle and presence of the sacralization. And there was a linear correlation between the degree of the pseudodisc and the vertebral slippage.