Rats were given low fluoride diets labelled with radiocalcium and either deionized water or deionized water containing 25 ppm fluoride. The percentage of calcium and specific activity (45Ca/mg40Ca) of auditory ossicles were determined. An effect of fluoride on the calcium metabolism of normal auditory ossicles was demonstrated. The stapedes of animals receiving low fluoride water contained more calcium at 6 wk than the stapedes of animals of both groups sacrificed at 9 wk, and the comparative specific activities of 45Ca suggest that the turnover of the calcium in ossicles from animals of high fluoride intake at 9 wk of age is less than those of the low fluoride animals. The ratio of the specific activity of the stapes to the specific activity of the incus or malleus demonstrated that the stapes is a much more metabolically active bone than the other ossicles.