In a prospective population-based investigation, we measured bone mineral density (BMD) of the forearm using single-photon absorptiometry at both a distal and a more proximal site in 74 Colles'-fracture patients who were compared with controls matched for age, sex, and years after menopause. For both groups there was a marked inverse relationship between age and bone mass. However, over the entire age range, the probands had 11 percent reduced BMD when compared with the controls. Our findings confirm that patients with fracture of the distal forearm have reduced BMD. They constitute an appropriate group for studies aimed at prevention of fracture in the elderly.