376 three-year old children were divided into four experimental groups and exposed to different combinations of preventive programs for a period of two years. All the groups were given the same basic prophylactic information. Additionally Group I received fluoride tablets (FLUDENT) for daily sucking twice a day plus a placebo dentifrice free of fluoride. Group II was given a fluoride dentifrice containing 0.025% F, (ACTA). Group III was given a placebo dentifrice plus fluoride varnish (Duraphat) twice a year. Group IV a fluoride dentifrice containing 0.025% F (ACTA) plus fluoride varnish (Duraphat) twice a year. No statistically significant difference in caries increment during the two experimental years was found between the groups. A tendency to lower caries increment was found in Group IV, i.e. in the children using the low fluoride dentifrice and treated twice a year with fluoride varnish.