is now known that normal intestinal bacteriocenosis consists of bacilli and cocci. The elaboration of probiotic biopreparations, intended to reconstitute its deregulated composition, is mainly carried out with the use of bacteria in the form of bacilli, and of cocci - very limited (only Enterococcus faecium species). The aim of the present work was to study the background of intestinal streptococci in healthy children of various ages and to argue their use in the development of microbial composition of new probiotic biopreparations. The investigations were carried out in several steps. The first was devoted to the isolation of streptococci currently existing in the healthy intestinal contents; the second to their identification and the third - to the calculation of the percentage share of various genera of intestinal streptococci specific to children of various ages. As a result, 834 streptococcal monotypic isolates were isolated and assigned to three genera of the Streptococcaceae family. The percentage share was higher in streptococci specific to children aged 1-3 years (genus Lactococcus), constituting 46.31-46.98%. In second place were those of the genus Streptococcus (31.57-37.73 %) and third - Enterococcus (18.6622.10 %). In children aged 5-16 years, there was a predominance of enterococci (38.1846.77%), a sharp decrease in lactococci (28.18-13.70 %) and a relative maintenance of those of the genus Streptococcus (33.92-39.51 %). Thus, in healthy children of various ages it was found: - the incidence of some intestinal representatives of the family Streptococcaceae; - their genus membership and the percentage share of streptococci of the genera useful to the body. It was demonstrated the opportunity of recommendation and differentiated use of streptococci from the studied genera in case of elaboration of new composition of probiotic biopreparations, intended for children of 1-3 years (genus Lactococcus), 5-16 years - (Enterococcus) and 1-16 years - (Streptococcus).