Fluoride salts are the currently most effective stimulators of the osteoblasts. Since the therapeutic effect depends on the concentration of fluoride ions achieved in the plasma, differences in fluoride content and bioavailability must be taken into account when using sodium fluoride or sodium monofluorophosphate. The optimal therapeutic range is assumed to be 10 to 20 mg bioavailable fluoride ions daily. The classical indication for fluoride is manifest osteoporosis in the elderly woman with fractures of the vertebrae. Available data, however, suggest that its early use in both men and women, as also in corticoid-induced osteoporosis, is justified. Under long-term treatment with fluoride, the bone mass of the vertebrae increases dose-dependently and linearly. At very high doses of fluoride, the quality of the newly formed bone-which is often excessive is presumably initially inadequate. A moderate increase in bony substance of about 4 to 6% a year is the therapeutic objective. Regular physical exercise and gymnastics, together with requirement-related supplementation with calcium and vitamin D ensures an improvement in the mechanical stability of the bone, and thus the desired reduction in the fracture risk.