Serum concentrations of magnesium, zinc and copper were measured in postmenopausal women with osteoporosis (n = 40), osteopenia (n = 40) or normal bone mineral density (n = 40) as classified on the basis of the T-score of the femur neck and dual energy X-ray absorptiometry results. Mean concentrations of magnesium and zinc were significantly lower in osteoporotic women than in both osteopenic women and normal women. In addition, magnesium and zinc concentrations in osteopenic women were significantly lower than in normal women. There were no statistically significant differences observed between the osteopenic, osteoporotic and control groups with respect to copper levels. The clinical significance of these changes needs further elucidation, but trace element supplementation, especially with magnesium and zinc and perhaps copper, may have beneficial effects on bone density.