Background and Aim: Although osteoporosis is not common in children and adolescents bone mineral density (BMD) studies in early life can be good predictors for this disease in the future. The aim of this study was to provide reference data of Dual X-ray Absorptiometry (DXA) for a population aged 10 to 20 years, in Tehran.

 Materials and Methods: 187 healthy people between 10-20 years of age were entered into this study randomly. Using DXA, BMD of femoral neck and lumbar vertebrae (L1-L4) (anteroposterior) were measured. Stage of puberty was determined and questionnaires about daily calcium intake were filled out. Serum levels of calcium, phosphate, vitamin D, parathyroid hormone and alkaline phosphatase were determined in all participants.

 Results: BMD values showed a positive correlation with age, height, weight and puberty stage. Calcium intake showed a correlation with BMD values of femoral neck, but not of lumbar region. In lumbar region, girls up to age of 18 had higher BMD values. In femoral region, boys had higher BMD values in all age groups. In neither regions, however, these differences were statistically significant. BMD increment at different stages of^�sexual development was statistically different only in stages 3 and 4 of puberty for both sexes in femoral and lumbar regions.

 Conclusion: Normative value curves developed in this study can serve as standards to predict bone mineral density.