Gastric intestinal absorption of five different preparations of sodium fluoride was measured by means of ten hour urinary excretion. Best absorption was by nonenteric coated sodium fluoride. All three enteric coated preparations showed poorer absorption, with marked individual variations. Florical,® the currently available preparation, showed better absorption than any enteric coated tablets and only slightly less than sodium fluoride alone. For active cochlear otospongiosis two capsules three times a day should be prescribed.