We determined broadband ultrasound attenuation (BUA) of the calcaneus, and bone mineral density (BMD) of the spine, proximal femur and radius in 137 healthy subjects (79 women and 58 men) and in 56 women with Colles' fracture. The repeated measurements on 9 healthy subjects indicated a short-term reproducibility (coefficient of variation) of 4 percent for BUA. There was a small (7 percent) but significant difference in BUA between normal men and women. The age-dependence in normal subjects was weak. When all the study subjects were pooled, modest correlations between BUA of the calcaneus and BMD at all measured skeletal sites were found (rs values 0.3-0.4). However, it was not possible to make an accurate prediction of the axial BMD, using BUA. BUA values were 13 percent lower in the wrist fracture patients than in the age-matched normals. In general, BUA could discriminate the fracture patients from normals as effectively as BMD. As suggested by the physical theory of ultrasound attenuation, our results support the idea that BUA reflects not only the bone density but also other factors related to the structural properties of bone.