Several prospective studies have shown that the bone mineral density (BMD) measured in the appendicular or axial skeleton has an inverse relationship with the risk of subsequent fractures. However, most of these studies have concentrated on relatively old age groups, and the usefulness of measuring BMD at the time of menopause has not been established. In the present study, BMD was measured at the lumbar spine and femoral neck by dual X-ray absorptiometry (DXA) in a random stratified population sample of 3222 perimenopausal women (mean age 53.4 years, range 47-59 years). These women were followed for fractures over a period of 2 years. The fractures reported by a postal inquiry were verified from medical records. Fractures sustained in motor vehicle accidents were excluded from the analyses. During a mean follow-up of 2.4 years, 183 fractures occurred in 168 women. Wrist (n = 47), ankle (n = 31), and rib (n = 28) were the most common sites of a fracture. Women in the lowest quartile of spinal BMD had a 2.9 times greater risk of fracture than those in the highest quartile. The respective risk increased 2.2 times from the lowest to the highest quartile of femoral BMD, respectively. The relative risk for suffering from any fracture per one SD decrease in BMD was 1.50 (95% CI; 1.27-1.76) for the spine and 1.41 (1.21-1.64) for the femoral neck. The present study demonstrates that bone mass is important in the pathogenesis of fractures even in perimenopausal women. We conclude that the axial BMD measurement at the time of menopause can be of use in predicting subsequent fracture risk.