We performed ultrasound measurements (QUS) of the calcaneus in a population-based setting on 280 healthy children, aged 11-16 years, from a small urban area in southern Sweden. The results are compared with dual-energy X-ray absorptiometry (DXA) measurements in the total body, the lumbar spine and the hip, as well as single-energy X-ray absorptiometry (SXA) of the forearm. Normative data and correlations between the three different techniques were determined. We found significant correlations between QUS and age (r = 0.34-0.54), height (r = 0.13-0.56) and weight (r = 0.30-0.60), and between QUS and bone mineral density (BMD) measurements (r = 0.44-0.70). Boys increased all their bone mineral variables with age, whereas girls showed a decreasing trend from age 15 years. QUS had a significantly higher increase in standardized value with age than Ward's triangle BMD, but a significantly lower increase in standardized value with age than distal radius (cortical site) BMD. At other BMD sites we did not find any significant differences compared with QUS regarding changes with age. The measurements obtained by QUS, DXA and SXA, respectively, were divided into, quartiles. Of all subjects in the lowest quartile for QUS measurements, only 34-50% were also in the lowest quartiles for DXA and SXA measurements. In conclusion, QUS measurements of the calcaneus in children show similar results as for adult regarding the correlation with DXA and SXA; they also have a significant correlation with anthropometric data. QUS did not identify the same individuals with low bone mass as the X-ray techniques.