The association between quantitative ultrasound (QUS) and bone turnover in postmenopausal women of different ages is an area of continuous investigation. The aim of this study was to investigate the relationship of ultrasound parameters [broadband ultrasound attenuation (BUA) and speed of sound (SOS)] to bone mineral density (BMD) and biochemical markers of bone turnover in three age groups of postmenopausal women. One hundred and twenty-three postmenopausal Caucasian women were divided into three groups according to their age: group A, range 44-54 years, mean age (+/-SD) 48.3 +/- 2.3; group B, range 55-65 years, mean age 59.4 +/- 2.1; and group C, range 66-77 years, mean age 68.2 +/- 3.1. Ultrasound parameters were measured by the DTU-one imaging ultrasonometer in the calcaneus. BMD was assessed by dual-energy X-ray absorptiometry (DEXA) at the lumbar spine, femoral neck, and trochanter. Bone turnover was assessed by serum bone-specific alkaline phosphatase (BAP), urinary excretion of free deoxypyridinoline, N-telopeptides (NTX), and C-telopeptide breakdown products of type I collagen (CTX). QUS and BMD were significantly correlated in all sites, except hip BMD in group A. The most significant correlation was observed between BUA and femoral neck BMD in group C (r = 0.626, p < 0.01). BUA correlated significantly with BAP, NTX, and CTX (r = -0.434, -0.511, -0.478, respectively; p < 0.01), and SOS with BAP and NTX (r = -0.351 and -0.356, respectively; p < 0.05) only in group C. In groups A and B, ultrasound parameters did not correlate significantly to biochemical markers. Ultrasound parameters were better correlated to hip BMD and to biochemical markers of bone turnover in elderly postmenopausal women. These ultrasound measurements could be used as a screening test for bone status, either in nonambulatory third aged women or in those living in rural areas where attending medical centers with DEXA equipment and biochemical laboratories is difficult.