The present paper reviews some of our current knowledge on fluoride-apatite interactions in bone tissue. Nearly all the dietary fluoride retained by the body is found in the apatitic component of hard tissue mineral. Fluoride's strong affinity for the hydroxyl lattice sites of apatite largely accounts for this mineral seeking property. Studies done during the past few decades have revealed that fluoride uptake is accompanied by numerous changes in the physical and chemical properties of bone apatite. Such changes include altered rates of formation and dissolution, increased crystallinity, concomitant reduction in crystal surface area, reduced solubility, and altered magnesium, carbonate and citrate levels. Additional studies on synthetic model systems have elucidated possible inorganic pathways by which some of these changes in mineral properties can be affected by fluoride. However, the total effect of fluoride on apatite formation in vivo is too complex to be interpreted in physicochemical terms alone. Biological factors appear to play an equally important role, especially with respect to crystallinity changes. © 1979.