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 normal volunteers(20-60years) were selected as a control group and 28 patients with developmental lumbar spinal stenosis were 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 of metabolic 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. We measured bone mineral density(BMD) at the cancellous bone of L1, 2, 3 and obtained the mean and its one standard deviation, 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 control subgroup(P<0.05). CONCLUSION: Developmental lumbar spinal stenosis in a young male may be a factor of decreasing BMD of the body of the spine.