Introduction. Dental caries is a frequent condition of the human population and the mechanism by which some individuals are susceptible to dental caries (DC) and others are caries resistant is of major interest to researchers. The purpose of the work. Evaluation the relationship between the level of serum immunoglobulin A (sIgA) in the oral fluid (OF) and children's susceptibility to DC. Material and methods. In the case-control clinical study were examined 198 children between the ages of 4 and 14, divided into 2 identical groups according to structure. In the research group (L1) were included 99 children with severe carious activity and the control group (L0) was made up of 99 children without dental caries. Were evaluated dental caries prevalence indices and carious experience indices dft, dfs, DMFT and DMFS. The sIgA level was determined by the immunoenzymatic analysis method on a solid support using the reagents of OOO Vectior-Best (Russia) and in accordance with the manufacturer's recommendations. Results. Was estimated statistically significant inverse relationship between the sIgA content in the OF and the DMFT, DMFS caries experience indices in the L1 group children. Conclusions. The estimated statistically significant relationship between sIgA content in OF and indices of caries experience confirms the previously launched hypothesis that sIgA level in OF is a salivary biomarker of the rampant evolution of DC. Thus, the significant decrease in the level of sIgA in FO detected in children affected by DC needs to be taken into account when planning individualized preventive measures.