The aims of this study were: 1) to determine bone mineral density (BMD) in different age groups, 2) to determine the prevalence of low BMD, and 3) to determine the possible association between BMD and a number of risk factors in Norwegian premenopausal women. BMD of the lumbar spine (L(2)-L(4)), total body, and the hip (total femur, femur neck, and trochanter) were measured using dual-energy X-ray absorptiometry (Prodigy, Lunar) in 145 randomly selected women aged 13-39 years. Information on other factors thought to influence BMD was obtained through questionnaire and a clinical interview. The group aged 25-29 years had the highest mean BMD in the total body, lumbar spine, and total femur while the group aged 13-19 years had the highest mean BMD in the femur neck and the trochanter. The mean BMD values of Norwegian premenopausal women were 3.4-5.1% higher than US/European reference data (P