This study describes the prevalence of osteoporosis in a statewide sample of nursing home residents. Composite forearm bone mineral density (BMD) (including the distal radius and the distal ulna) of 1475 residents aged 65 years and older from 34 randomly selected, stratified nursing homes was assessed. BMD was expressed with reference to World Health Organization diagnostic criteria. Trends with age, gender and race were consistent with other populations. However, prevalence estimates were higher than community-based age-specific rates. The prevalence of osteoporosis for white female residents increased from 63.5% for women aged 65-74 years to 85.8% for women over 85 years of age. Only 3% had composite forearm BMD within 1 standard deviation of the young adult mean. The significance of the high prevalence of low BMD in nursing home residents is the increased fracture risk it may confer. In community cohorts of white women, the risk of hip fracture increases approximately 50% for every 1 standard deviation decrease in bone mass. However, the degree to which BMD contributes to fracture risk in this population has not been well established.