The enteric nervous system is part of the peripheral nervous system and innervates all layers of the digestive tract, from the esophagus to the anus. It is regulated by both the parasympathetic and sympathetic autonomic nervous system, but it can also perform certain functions independently of the brain and spinal cord. It is essential for the regulation of motility, secretion and immune responses of the digestive system and serves as a mediator between the intestinal microbiota and the central nervous system. It is made up of two plexuses: the submucosal and the myenteric plexus, which communicate with each other and with other parts of the nervous system. They are built from a large number of neurons and enteroglial cells that together form complex neural circuits. The enteric nervous system is regulated by various neurotransmitters and active substances such as acetylcholine, serotonin, dopamine, substance P and vasoactive intestinal peptide. Studies have shown the direct influence of intestinal microbiota on the enteric nervous system, through which it affects the entire organism. Changes in the composition of the normal intestinal microbiota can lead to disorders of intestinal functions (such as secretion and motility), phenotypic changes of neurons, but also to behavioral disorders and neurological diseases. The most numerous microorganisms found inside the digestive system are bacteria, which can be commensal or pathogenic, neurotropic viruses and protozoa.