The present study was designed to investigate the influence of modifiable risk factors (body weight and lifestyle) for bone loss on bone mineral density (BMD). We examined age-specific changes in metacarpal BMD, and its associations with body mass index and lifestyle among 532 community-dwelling postmenopausal Japanese women. Measurements of the second metacarpal BMD were obtained from the hand radiographs using computer-assisted radiographic absorptiometry. Body height and weight were measured, and body mass index (BMI) was calculated. Physical activity index was calculated using validated questionnaire. Daily calcium intake and amount of ingested alcohol were estimated by semiquantitative food frequency questionnaire. Current smoking status was obtained by questionnaire. Metacarpal BMD decreased significantly with increasing age. Simple correlation analysis indicated that metacarpal BMD correlated significantly with BMI and physical activity index. On the other hand, metacarpal BMD did not correlate with calcium intake and alcohol drinking. Metacarpal BMD in current smokers was not different from that in nonsmokers. Multiple regression analysis showed that increasing age was associated with decreased metacarpal BMD and greater BMI increased metacarpal BMD. However, physical activity, calcium intake, alcohol drinking and current smoking were not significant determinants of metacarpal BMD. Our findings suggest that maintenance of adequate body mass (prevention for leanness) is important for prevention of postmenopausal bone loss.