Purpose : The purpose of this study is to evaluate the relationship between developmental lumbar spinalstenosis and its BMD value by using the single energy quantitative CT(SEQCT). Materials & Methods : Eighty normalvolunteers(20-60years) were selected as a control group and 28 patients with developmental lumbar spinal stenosiswere selected as a disease group. The two groups were divided into a younger (20-39years) and an older subgroup(40-60 years), and were further divided into male and female subgroups. All the cases showed no evidence ofmetabolic disease, fracture, herniated nucleus pulposus, degererative spondylosis, infectious disease, tumors orhad no history of absolute immobilization of more than two weeks. All underwent lumbar spine CT and SEQCT. Wemeasured bone mineral density(BMD) at the cancellous bone of L1, 2, 3 and obtained the mean and its one standarddeviation, and compared the data between each subgroup of the control and the disease group using ANOVA. Results :There was a significant low BMD value in the younger male patient subgroup compared with the controlsubgroup(P<0.05). Conclusion : Developmental lumbar spinal stenosis in a young male may be a factor of decreasingBMD of the body of the spine.