Microbiome co-evolved with its human host for a long time and became essential for many processes. Bacteria play role in maintaining human health as they digest food, produce vitamins and participate in regulation of metabolism. By influencing cytokine balance along with composition and activity of leukocytes, they constantly interact with immune system affecting innate and adaptive immune homeostasis. Growing number of evidence indicates that microbiome of human intestine may have an impact on the functions of CNS, through identified pathways named as gut-brain axis. Recent data show that ecosystem of human microbiome interferes with brain’s development, central signaling systems and behavior. It has been proposed that disruption of the human microbiome may contribute to the course of psychiatric disorders. The aim of this review is to summarize recognized pathways of gut-brain axis that were thoroughly studied in animals models and to evaluate the role of the dialogue between microbiota and central nervous system in schizophrenia, bipolar disorder and depression