The prevalence of small intestinal bacterial overgrowth (SIBO) is increasing worldwide, especially in countries with high rates of urbanization. The growth of pathogenic and/or opportunistic bacteria in the small intestine can cause clinical symptoms and digestive and absorption disorders. The aim of the review was to analyze available literature on SIBO in various gastrointestinal pathologies. Material and methods. A literature search was conducted for the last 10 years using the library platforms PubMed, Medscape by keywords: "small intestinal bacterial overgrowth", "SIBO". A total of 1112 scientific papers were found, of which 124 English-language and 28 Russian-language publications were subject to analysis. Of these, 41 articles (including 5 Russian-language ones) corresponding to the topic of this review were included in the review. Results. The article presents data reflecting the pathophysiology and factors contributing to the development of SIBO. It is shown that irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and a number of organic and functional diseases of the gastrointestinal tract (GIT) are closely associated with SIBO. The features of the pathogenesis of SIBO in gastrointestinal diseases (IBS, IBD, functional dyspepsia, celiac disease, non-alcoholic steatohepatitis, chronic pancreatitis, etc.) and its influence on the course of gastrointestinal pathology are described. Conclusion. It is impossible to unambiguously assess the influence that SIBO and various types of gastrointestinal pathology have on each other, since, on the one hand, SIBO can develop as a result of gastrointestinal diseases, and on the other hand, it can serve a predictor of the deterioration of these diseases. Most likely, we are talking about the emergence of a vicious circle, to break which it is necessary to eradicate the microorganisms that cause SIBO. This can be achieved both through drug treatment and by adjusting the diet of patients. An important element of non-specific prevention of SIBO is also timely rational treatment of gastrointestinal diseases that contribute to the development of this syndrome.