OBJECTIVES: The incidence of osteoporosis in Korea has increased rapidly, however there are no reference values for bone mineral density (BMD) in the Korean population. We analyzed the BMD data of Koreans based on age, gender, and region. METHODS: We reviewed BMD data (L-spine, n=50,208; femur, n=50,026) that was obtained in hospitals in Korea between 2003 and 2004. BMD was measured using QDR 4000 and QDR 4500 systems (Hologic, USA). RESULTS: The mean lumbar BMD in females in the 35-44-year-age group was 985+/-129 mg/cm2 and had the highest values compared to other age groups. The BMD decreased rapidly in the menopause. The mean lumbar BMD in males peaked in the 25-34-year-age group. The mean BMD in females and males peaked in the 35-44-year-age group (864+/-114 mg/cm2) and 25-34-year-age group (960+/-133 mg/cm2), respectively. The mean lumbar BMD of urban residents was higher than the mean lumbar BMD rural residents after 45 years of age. CONCLUSION: In the Korean population, the peak BMD was achieved at approximately 30 and 40 years of age in males and females, respectively. There were differences in the mean BMD between urban and rural regions in the elderly age group.