Serum 1.25 dihydroxyvitamin D concentrations were reduced in elderly patients with femoral neck fractures, irrespective of the presence of osteomalacia. This reduction was not attributable to a decrease in vitamin D binding protein. The low rate of bone turnover in these elderly patients might reduce the requirement for vitamin D and protect against the development of osteomalacia. Serum vitamin D metabolite concentration cannot be used as a screening test for osteomalacia in these patients.