At present, Dual Energy X-ray Absorptiometry (DEXA) method is a reference method to diagnose osteoporosis. This method allows to measure bone density and bone mass, however bone quality can not be estimated. Quantitative ultrasound (QUS) method provides information about bone structure. The aim of our work was the evaluation of QUS method in healthy children, establishing reference values in cross-sectional study of healthy children aged 7-18 yrs and to examine the annual change of ultrasound parameters in prospective study at pubertal. Group of 530 girls and 369 boys was recruited from Warsaw schools, and right heel was measured with Achilles Plus apparatus. Measurements were repeated after 1 year, in a subgroup of 153 children aged 9-13 yrs. The method was adapted for paediatric measurements by using limiter of ultrasonic wave and pads for positioning foot in water chamber. Speed of sound (SOS) and broadband ultrasound attenuation (BUA) were measured and Stiffness index was calculated. Width of heel, at the same location as QUS measurement, was also measured using calipers. SOS, BUA and Stiffness values increased by age in boys and girls. BUA and Stiffness values were significantly higher in 15, 16 and 17 year old boys than in age-matched girls (in 18 yrs--only Stiffness). However, there were no significant sex differences in annual increase of SOS, BUA and Stiffness, although the biggest increase was observed between the age of 13-14 yrs for boys and 11-12 yrs for girls. That may reflect pubertal spurt of body growth but that relationship was not confirmed by annual increases calculated from cross-sectional data. Statistically significant correlation of SOS, BUA and Stiffness with body mass, height, body mass index (BMI) and heel width was observed. Normalization of SOS, BUA and Stiffness on heel width decreased force of that correlation but it was still statistically significant. Dynamics of SOS, BUA and Stiffness increase by age was higher in boys than in girls. This phenomenon is probably related to higher peak bone mass in men than in women, and lower risk of fracture in men, especially concerning hip. Increase of speed of sound, broadband ultrasound attenuation and stiffness index by age, and their correlations with body mass, height and body mass index reflects bone growth in children and adolescents. Broadband ultrasound attenuation and Stiffness index show sex differences in bone development in adolescence. Higher dynamics of the increase of speed of sound, broadband ultrasound attenuation and Stiffness index by age in boys confirms faster bone mass accumulation in boys than in girls.