The growth of nails, and their matrix components, are influenced by several physiological, pathological and environmental factors. Because of the slow rate of nail growth, the elemental composition of the nail is also expected to be affected by transient factors controlling serum components. The mineral components of nail clippings may therefore reflect the long-term patterns of mineral metabolism, such as the rise of creatinine concentration seen in nails in patients with renal failure with hypercreatinemia. Fingernail and toenail Ca concentrations decreased with age in both men and women, whereas Mg concentrations tended to increase. Postmenopausal women had lower finger nail Ca concentrations than premenopausal women. LBMD showed a significant positive correlation with finger nail Ca content. The measurement of finger nail Ca content may be useful as a predictor of osteoporosis.