The aim of this study was to investigate the longitudinal effect of mobility and daily activity, in the form of exercise and everyday activities, on the bones of 102 elderly female nursing home residents who had physical disabilities as well as marked postmenopausal bone loss, using calcaneal ultrasound apparatus for bone evaluation.Of the 102 subjects initially measured, 74 (mean age, 83.5H6.55 years; range, 64 99 years) could be measured again approximately one year later. The osteo sono-assessment index (OSI) in this study was determined using an ultrasound bone evaluation device. This device measures the speed of sound (SOS) and transmission index (TI) as ultrasound passes through the calcaneus. The OSI is calculated by computer analysis (OSI=TI`SOS 2 ). For mobility, the OSI decreased significantly by an average of 1.8% after 11.8 months in all of the residents who were using a wheelchair (n=41, p<0.01). In contrast, the OSI rose significantly by a mean of 1.9% in the ambulatory group (n=33, p<0.01).The OSI increased significantly in residents who exercised every day, were out of bed for at least seven hours per day, and walked on a regular basis, suggesting that exercise, mainly in the form of walking, may increase the calcaneal OSI.