Purpose : To evaluate the usefulness of supine lateral bone mineral density (BMD) measurement using DXA by comparing AP and lateral spine BMD in patients with degenerative change. Materials and Methods : Six hundred and seventy-two women underwent AP and lateral BMD measurement of L-spine, using DXA. Spur changes and end-plate sclerosis were considered as degenerative change, and osteoporosis was defined according to WHO criteria. The ratio of mid-lateral BMD to AP BMD was calculated and the differences in ratio were analyzed in the degenerative group and controls, according to aging and osteoporosis, using the t test and ANOVA. The correlation coefficiency between aging and AP BMD and lateral BMD, respectively, was calculated. Result : The mLat/AP ratio in the control and degenerative group was 0.710(0.005 / 0.622(0.028 (p=0.003) in the 40-49-year-old group, 0.663(0.006 /0.612(0.016 (p=0.002) in the 50-59-year-old group, 0.626(0.015 / 0.552(0.023 (p=0.007) in the 60-69 year-old group, and 0.717(0.028 / 0.600(0.045 (p=0.076) in those aged over 70. The ratio was 0.656(0.015 / 0.598(0.038(p=0.099) in osteoporosis, 0.684(0.008 / 0.596(0.016 (p=0.000) in osteopenia, and 0.688(0.005 / 0.583(0.019(p=0.000) in normal subjects, showing that lateral BMD is more sensitive than AP BMD, especially in the degenerative group. There was negative correlation between aging and AP BMD(r= -0.545), lateral BMD(r= -0.571), and mid-lateral BMD(r=-0.583). Conclusion : In a selective group of patients with degenerative change, supine lateral BMD measurement of L-spine is useful.