Study is devoted for rs1801270 polymorphism of CDKN1A gene due to the level of intensity of caries development in children with Down syndrome. The full development of oral cavity organs is ensured through a complex of genes whose protein products control different stages of this difficult process. Changes in gene structure, as well as disturbance of their expression may lead to abnormalities of development of teeth and periodontal tissues. Analysis of the polymorphism of CDKN1A gene Ser31Arg in children living in Kharkiv region has shown that the frequency of genotypes and alleles corresponds to the theoretically expected distribution by Hardy-Weinberg in the core (χ2=0.12) and control (χ2=1.29) groups. There is no significant differences in the frequency of alleles of CDKN1A gene in the group of healthy children and children with Down syndrome (p=0.978). There is an association of heterozygous option C/A of the studied marker Ser31Arg of CDKN1A gene with the level of intensity of caries development (by Leus) in children with Down syndrome under 10 years old.