The influence of different galactose concentrations on the cariogenic effect of Streptococcus mutans (strains: DSM 20381 and DSM 20523) in a sucrose diet (33%) was examined in an animal experiment. The treated Wistar rats were free of pathogenic germs at the beginning of the experiment. The experimental conditions were approximately in accordance with the "Consensus statement" of the American Dental Association. The sides of the teeth, the amount of film, the abrasion of the chewing surfaces, the amount of surface and fissure caries and the animals general condition were evaluated. The anticaries effectiveness of galactose is dependent on its concentration: 5.0% galactose reduces the amount of caries on a high significance level, lowers the abrasion of the chewing surfaces, possibly because of the increased amount of serum calcium related to this galactose concentration, and diminishes the amount of film. 1.5% galactose prevents caries significantly and strongly reduces the amount of film; 0.5% galactose reduces the amount of caries non-significantly, but diminishes the amount of film. The effect is based on the property of galactose to occupy the receptors of the pellicle (layer of glycoprotein on the tooth enamel), hence the adherence of specific germs (for example, Streptococcus mutans) ceases in whole or in part.