A randomized double-blind clinical trial was undertaken in a nonfluoridated community to assess the effectiveness of a minimal preventive intervention based on biannual applications of an amine fluoride (AmF) solution containing 1% fluoride. A total of 284 schoolchildren aged 6 years were recruited from a primary school in Milan, Italy, and randomly assigned to an experimental or a control group. The subjects of the experimental group received two applications each year of AmF to the permanent first molars and the control group subjects received similar applications of a placebo solution. Both in the experimental and control groups caries experience (DMFT) of the first molars was recorded every 6 months for 5 years. The mean DMFT scores in the experimental and control group were, respectively, 0.56 and 0.22 at the beginning and 1.14 and 1.75 at the end of the study. The preventive effect of the treatment became statistically significant only after 3 years. Survival analysis performed on the first molars that were sound at baseline showed that the topical AmF treatment caused, after 5 years, a significant reduction of caries incidence. This result confirms observations found in the international literature on the anticaries action of AmF. The administration rate used in this study seems to be useful for community preventive applications as it reduces the total amount of fluoride administered and the potential risks, and involves few personnel.