We describe a detailed study of fluoride distribution with age in the human cortical rib bone. Human ribs were obtained from 110 subjects (M:68,F;42) aged 20–93 years. The fluoride distribution from the periosteal to endosteal surfaces of the ribs was determined by sampling each specimen using an abrasive micro-sampling technique, and the samples were analyzed using the fluoride electrode, as described by Weatherell et al. . The concentration of fluoride was highest in the periosteal region, decreased gradually towards the interior of the tissue where the concentration of fluoride tended toward the plateau, and then rose again towards the endosteal surface. Patterns of fluoride distribution changed with age, and the difference between periosteal and endosteal fluoride levels increased with age. Although average fluoride concentrations increased with age in both sexes, there was a significant difference between males and females at the age of about 55 years (P<0.05).