Aim of this study was to investigate the efficacy of prophylactic use of a liquid probiotic form based on Enterococcus faecium L3 in children first year of life to increase resistance to acute respiratory infections (ARI) in the winter-spring period and improve nutritional status. In a specialized (psychoneurologic) orphanage of St. Petersburg within three months of winter-spring period in 2014 observed 29 children in the first year of life. Observed children were randomly divided into two groups. The main group (n = 14) within three months received daily per os liquid probiotic form based on E.faecium L3 in a daily dose of 1.5 x 10(9) CFU. A control group of children (n = 15) was comparable with the main group by gender and age. The children observed groups studied the incidence of ARI; number of vaccinated children; the number of children who received two or more vaccinations at the same time; the number of children with acute infectious diseases within 1 month after vaccination; dynamics of Chulitskaya index, body mass index, body weight and length. The data obtained are subjected to statistical analysis, the results were considered significant at p < 0.05. The results showed that the use of probiotic forms E.faecium L3 in infants helped to reduce the average number of ARI cases per child (0.29 ± 0.13 vs. 0.73 ± 0.12 in the control group; p < 0.05) only in the first month of the observation that combined with a significantly higher BMI values increase this month (0.54 ± 0.25 vs. 0.07 ± 0.22 kg/m2 in the control group; p < 0.05). Use the liquid probiotic form E.faecium L3 in infants had a positive impact on overall health, which is reflected in the implementation of routine vaccination activities--in the main group, the number of children who received two or more vaccinations at the same time was 18.1% more.