Poor posture can create abnormal stress concentration which can be one of the major causes of low back pain. Also we believe that the restoration of the normal pelvic inclination is one of the key factors to overcome postural deformity and pelvic tilt exercises have been regarded as one of the important components of back exercises. We can expect a decrease in the pelvic tilt angle and the relaxation of the iliopsoas muscle with the elevation of one leg. In this sense, lateral views of the lumboscral spine were evaluated in 15 young males with relation to the postural changes, such as with one foot elevated to 1/3 leg length height and 2/3 of leg length hight and with one foot placed forward. Several radiologic parameters and the pelvis were analyzed statistically with a SPSS package. Various radiological parameters were measured accoding to During's radiological abservations. Multiple regression was used in order to estabilish the existence of mutual dependencies between several characteristics of posture and to formulate relations between the pelvis and the lumbar spine system, beyond the descriptive analysis. Results of this analysis with relation to elevation of one leg are as follows;The pelvic tilt was decresed with one leg elevated or the foot placed forward. However, compared with the normal standing posture, all other radiological parameters were decreased by the elevation of one leg, but not by its degree. The declivity of the upper surface of the sacrum and the pelvisacral angle determine the pelvic tilt directly and the lumbosacral angle and the radius of the lumbar lordosis could affect the pelvic tilt indirectly. In a normal standing posture, the declivity of the upper surface of the sacrum is suspected as the single key determinent for posture. Thus, a postural reflex to prevent and manage low back pain syndromes could be done by effective control of the declivity of the upper surface ot the sacrum.