Summary: The paper summarizes the results of studies dealing with genetic conformity of S. mutans between children and their parents, between children and both parents or between parents. As fas as the conformity of S. mutans genotypes between children and parents are concerned, there were more frequent in the pair of mother/ child than in the pair father/child, where continental differences were observed. In cases of European groups, where there was conformity of S. mutans genotype between the parent the child, it proved to concern the mother and child pair in 70% of cases. There was no conformity in the father and child pair in European studies repeatedly, whereas the Japanese father and child pairs proved to agree in 31.4 of the examined families. Homologous clones of S. mutans were found in 10 to 15% of the parents pairs only. The children suffering from higher caries rate of the primary teeth proved to have more S. mutans genotypes than those with low caries rate or with in tact teeth.

        Key words: oral streptococci – S. mutans – transfer of cariogenic streptococci – genotype identification of cariogenic streptococci