In 1969, a caries preventive program was initiated in a part of Denmark where parents of infants were offered prescriptions for fluoride tablets for daily use. When requested new prescriptions were supplied free of charge by the County Dental Officer. In 1976, samples of children about 7 years of age who had received a total of 0, 1–800, 800–1,600 and more than 1,600 0.25 mg F tablets were examined. A positive association between number of tablets prescribed and dental fluorosis was found in erupted permanent teeth. The frequency of localized enamel opacities was similar in the four study groups. A significant inhibition of dental caries in the primary dentition was recorded only for those, who in total received more than 1,600 tablets and used them continuously through the years. No difference in caries was observed in the permanent dentition. The findings indicate in accordance with current theories that topical effects of fluoride rather than the systemic effects have prevented dental car