The aim of the study was to establish the normative QUS data in a healthy sample of Croatian males and estimate the prevalence of osteoporosis. A total of 1002 male participants, aged 20-99, were recruited in seven study centers (Zagreb, Ivanić-grad, Koprivnica, Sibenik, Pula, Slavonski Brod, Vukovar). In each subject broadband ultrasound attenuation (BUA), speed of sound (SOS) and quantitative ... [Show full abstract] ultrasound index (QUI) of the calcaneus were measured using the Sahara ultrasound device. Significant declining with age was found for all three parameters (p < 0.001). The peak SOS (1562.8 +/- 28.5 m/s) and QUI (103.6 +/- 16.5) values were observed in the third decade, whereas the peak BUA value (86.2 +/- 19.2 db/MHz) was observed in the fourth decade of life. Using the World Health Organization diagnostic criteria for DXA the rates of osteoporosis in the males aged 50 and older were 5.8%, 3.4 and 4.2% for QUI, BUA, and SOS respectively. However, when we used the cut-off value of the T < or = -l.8, prevalence of osteoporosis in Croatian males older than 50 years was 16.2%, 11.7% and 17.2%.