OBJECTIVE The aim of the study was to assess the caries inhibition effect of fluoride varnishes among preschool children with high caries risk. At the same time, the suitability of this measure should be examined in the frame of group prevention programmes in kindergartens. METHODS This was an examiner-blind, clinically controlled 2-year study with 200 randomly selected 2- to 4-year-old preschool children with high caries risk. At the baseline, caries-free surfaces, initial caries lesions as well as the caries status (dmfs) were recorded. After the baseline, all subjects were divided into 3 groups. Subjects of group A received every 6 months (altogether four times) applications with the fluoride varnish Fluoridin N5 (VOCO GmbH, Cuxhaven, Germany), children of the group B received every 6 months (altogether four times) applications with Duraphat (Colgate Palmolive GmbH, Hamburg, Germany), while the subjects of group C did not receive any fluoride varnish applications and constituted the control group. A final examination was performed after two years similar to the baseline. Statistical analysis was based on the SPSS programme at a significance level of 95%. CONCLUSIONS The results confirmed the caries inhibition efficacy of both fluoride varnishes. This is shown as well in the almost constant number of caries-free surfaces and initial caries lesions in the two F-groups during the observation period. The caries-free surfaces in group C were significantly reduced along with an increase of initial caries lesions. The caries reduction, based on the control group, amounted in group A to 56% and in group B to 57%. The results documented the caries inhibition effect of both fluoride varnishes which are suitable for intensive group prevention programmes for pre-school children.