The aim of the study is to study the clinical and microbiological characteristics of newborn children and their mothers to improve the diagnosis of intrauterine infections. Materials and methods. A retrospective (2011-2019) analysis of the results of microbiological studies of biomaterials from newborns and their mothers in 63 cases of early neonatal mortality with established diagnoses of intrauterine infection was carried out. Results. In the study of material from women in labor (samples of the placenta and amniotic fluid, detached cervical canal), coagulase-negative staphylococci were most often isolated, among which Staphylococcus epidermidis dominated. Streptococcus agalactiae was more often found in the biomaterial of the placenta and amniotic fluid in comparison with the material from the cervical canal. Conclusions. Microbiological examination allows to confirm the presence of the pathogen and its transmission from the mother to the fetus/newborn only in 30% of cases. Even in cases of high contamination of the genital tract of the postpartum woman, the study of materials from the newborn immediately after birth often does not give a positive result due to the low degree of contamination at the initial stage of the development of the infectious process and the appointment of antibiotic therapy during childbirth. An increase in the diagnostic value of microbiological research can be facilitated by an increase in the frequency of examinations, the number of samples taken; the use of techniques that increase the sensitivity of the culture study at the stage of the analysis; the use of molecular genetic methods, especially in the study of materials from newborns.