CT scanogram is a new technique for measuring leg length discrepancy and has many advantages as compared with conventional spot scanogram. 30 dried bones wetre measured by direct measurement, spot scanogram and CT scanogram. Accuracy of CT scanogram was compared with spot scanogram. For evaluation of systemic error of CT, steel rulers and dried bones were measured at two different window settings. Decentering error in spot scanogram was measured by using dried bones and 180 spots of 30 clinical cases of Bell-Thompson studies were reviewed for evaluation of incidence and degree of decentering. The results of measurements of CT and spot scanogram in ideal position and technique were equivalent to those of direct measurements. But in spot scanogram, significant errors were neoted in flexion status and decentered film. 54 spots of 30 clinical cases were decentered more than 1cm. In CT scanogram, decentering error was completely excluded and shortening due to flexion deformity was vercomed by lateral scanogram. CT scanogram is a simple and accurate method for leg length measurement. Thus we recommend CT scanogram as a routine use for evaluation of leg length discrepancy.