In this review new scientific technologies (genomics, proteomics, metabolomics, transcrip- tomics) were used to evaluate the prophylactic and therapeutic action of probiotics, which are a major component ofthe normal human microflora (microbiota). Modern terms, definitions, classification of probiotic preparations are provided in the paper, the list of the probiotics registered in the Russian Federation is also submitted. The review analyzes the majority of mechanisms of probiotics action on a human body. The problem of safe application of probiotics is considered along with the detailed characteristic of the most effective production probiotic strains. New scientific technology to assess the effects of probiotic bacteria on the various functions of the macroorganism are also examined. In the review the special attention is paid to discussion of effectiveness of the probiotics impact in chronic infectious and metabolic disease processes (atherosclerosis, lipid distress syndrome, type 2 diabetes, obesity, etc.), which are the most active during dysbacteriosis and the destruction of normal microflora. From data of this article clearly that new scientific technologies will allow us to establish the functions of proteins that regulate metabolic and signaling pathways and affect the expression of genes required for the adaptation of probiotic strains in contact with the human body. In this review it is shown that the successful solution of this problem is closely connected with application of new scientific technologies for studying the composition and functions of the human microbiota, methods of active influence on her, and also with development of more sophisticated and effective probiotic preparations.