24, 24-Difluoro-1α, 25-dihydroxyvitamin D3 (1) has been synthesized from 24, 24-difluoro-5β-cholestane-3α, 25-diol (2) as an antimetabolic analogue of 1α, 25-dihydroxyvitamin D3 to study the role of the 24-hydroxylation in the metabolism of vitamin D3.