Summary: Irritable bowel syndrome (IBS) belongs to a group of diseases formerly known as functional disorders and now referred to as disorders of the gut-brain axis. IBS is one of the most common conditions in this field. The prevalence of IBS is about 11% of the population worldwide, although this varies from country to country and latitude to latitude. IBS causes significant discomfort that reduces quality of life and often poses difficulties in differentiating it from organic diseases. The diagnosis is established on the basis of the Rome IV Criteria, but in the presence of alarming symptoms, family history, and patients' age >50 years, a deeper diagnosis is necessary. Genetic factors, environmental factors, psychosocial factors, abnormalities of the intestinal microbiota and the resulting microinflammation, motility disorders and visceral hypersensitivity play a role in the pathogenesis. In the absence of a single etiologic factor, treatment of IBS consists of reducing the severity of symptoms and improving the quality of life of patients, with efforts to favorably modify the intestinal microbiota appearing to be an important therapeutic goal. Symptomatic pharmacotherapy includes the use of diastolic and motility-regulating drugs, and antidepressants have also been shown to be effective when used as a second-choice line, confirming that functional illnesses are a manifestation of gut-brain axis dysfunction. Given the important role of the intestinal microbiota, a strategy for its beneficial modification includes the use of eubiotics for IBS without predominant constipation and probiotic therapy, but not microbiota transplantation from a healthy donor.