The caries-preventive effect of semiannual applications of a fluoride varnish (Duraphat) was tested for 2 years in 225 3-year-old children; 113 children served as a control group. At the baseline examination, 69% of the children in the test group and 75% in the control group were caries-free. The results after 2 years showed an average caries increment of 2.1 surfaces in the test group and 3.7 in the control group. The difference is statistically significant. Thirty-eight percent of the children in the test group and 27% in the control group were still caries-free. The caries reduction was 44%.