The study aimed at determining precision and accuracy of the ultrasound technique measuring bone mineral density in the calcaneus bone in children. Bone densitometer of Achilles type was adapted for measurements in children. Ultrasound beam was narrowed and a system of special pads positioning the foot were used for this purpose. Precision (CV (%) SOS: phantom 0.42, patients -0.42; BUA: phantom 1.46, patients -3.03) and accuracy of this technique were determined in comparison with dual energy X-ray absorptiometry as well as its value in diagnosis of osteopenia in childhood. An increase in SOS and BUA with the age was found. A decrease in these parameters was noted in children with osteopenia, comparing with the values in healthy children. Significant correlations (r ranging from 0.50 to 0.91) between ultrasound and DEXA techniques were seen. The results suggest that ultrasound technique might be useful in pediatric densitometry.