To evaluate a relationship of lumbar lordosis between asymptomatic group and low back pain group, lumbar lordotic angle was measured from standing lateral lumbosacral roentogenogram of 360 men and women between 20 and 49 years of age. We excluded the patients with back deformity, moderate to severe degenerative change of lumbosacral spine, leg length discrepency, and degenerative change of lower leg in both groups. The lumber lordodsis angle was measured with two ways, lumbosacral angle and lumbolumbar angle respectively. Two angles have a line parallel to the top of second lumbar vertebra as the proximal boundary. The distal border of the lumbosacral angle is a line parallel to the top of sacrum. The distal border of the lumbolumbar angle is a line parallel to the bottom of fifth lumbar vertebra. With statistical analysis of the results, we came to followiing conclusion: 1. The mean lumbolumbar angle was 33.62° +0.62° (SEM: standard error of the mean) and the mean lumbosacral angle was 49.91° +0.59° in asymptomatic group. 2. The mean lumbolumbar angle was 34.79° +0.68° and the mean lumbosacral angle was 50.35° +0.76° in low back pain group. 3. No significant difference in lumbosacral and lumbolsacral angle between asymptomatic and low back pain group was identified using general linear models procedure(P>0.5). 4. Analyzing the data by sex, no significant difference in lumbosacral and lumbosacral angle was identified using general linear models procudure(P>0.05). 5. Analyzing the data by age group, no significant difference in lumbosacral angle was identified (P>0.05), but significant difference in lumbolsacral angle was identified using general linear models procedure(P=0.0045).