Osteoporosis is defined as a progressive systemic skeletal disorder characterized by low bone mineral density, microarchitectual deteriorations of bone and susceptibility to fracture. numerous methods have been used for quantitative assessment of the skeleton in osteoporosis. QCT has been shown to measure changes in trabecular mineral content in the spine with great sensitivity and precision. To provide the normal reference values and changes of lumbar spinal bone mineral density in korean adult spinal bone mineral density was evaluated in 451 women (229 premenopausal and 222 postmenopausal women) and 206 men, aged 20 to 74 years old in Wonkwang hospital from 2000 to 2004, which was carried out by using QCT. women with oophorectomy, vertebral compression fracture, any history of endocrine disease and use of drugs that alter bone metabolism were excluded. According to the WHO definition, a patient is osteoporotic based on a bone mineral density(BMD) measurement that is 2.5 standard deviations (SDs) below typical peak bone mass of young healthy white women. This measurement of standard deviation from peak mass is called the T score. BMD values of normal women in their 20-24 years, 25-29 years, 30-34 years, 35-39 years, 40-44 years, 45-49 years, 50-54 years, 55-59 years, 60-64 years, 65-69 years, over 70 years were 168.95㎎/㏄ K₂PHO₄, 155.41㎎/㏄ K₂PHO₄, 166.87㎎/㏄ K₂PHO₄, 160.67㎎/㏄ K₂PHO₄, 154.06㎎/㏄ K₂PHO₄, 132.04㎎/㏄ K₂PHO₄, 114.05㎎/㏄ K₂PHO₄, 91.78㎎/㏄ K₂PHO₄, 78.61 ㎎/㏄ K₂PHO₄, 61.35㎎/㏄ K₂PHO₄, 50.53㎎/㏄ K₂PHO₄ Mean bone density of normal women was 115.77K₂PHO₄ K₂PHO₄. BMD values of normal men in their 20-24 years, 25-29 years, 30-34 years, 35-39 years, 40-44 years, 45-49 years, 50-54 years, 55-59 years, 60-64 years, 65-69 years, over 70 years were 171.46㎎/㏄ K₂PHO₄, 162.19㎎/㏄ K₂PHO₄, 155.62㎎/㏄ K₂PHO₄, 147.28㎎/㏄ K₂PHO₄, 137.56㎎/㏄ K₂PHO₄, 137.56㎎/㏄ K₂PHO₄, 101.25㎎/㏄ K₂PHO₄, 109.00㎎/㏄ K₂PHO₄, 103.32㎎/㏄ K₂PHO₄, 91.53㎎/㏄ K₂PHO₄, 88.35㎎/㏄ K₂PHO₄ Mean density of normal men was 115.77㎎/㏄ K₂PHO₄. Peak bone density of women and men was in the age group of 20-24 years and 168.95㎎/㏄ K₂PHO₄, 171.46㎎/㏄ K₂PHO₄, respectively. Bone loss was increased with aging and was accelerated in postmenopausal women than that of premenopausal women. The total loss of BMD for women and men was 70.09% and 48.47%, respectively. Postmenopausal women(mean BMD : 85.83㎎/㏄ K₂PHO₄) had significantly lower BMD than premenopausal women(meand BMD : 144.80㎎/㏄ K₂PHO₄)(p<0.001). The annual loss of BMD of women and men was 2.702㎎/㏄ K₂PHO₄ and 1.795㎎/㏄ K₂PHO₄, respectively. This study provided the BMD reference data for normal korean adult. further studies on BMD in healthy adult and comparison with published data are needed.