The review describes the influence of serotonin (5-HT) and its receptor, transporter SERT and nuclear factor Nf-kB on the immune function of the body, particularly in the digestive tract. The mechanisms of the synthesis, metabolism and catab. olism of 5-HT are characterized. The targets for serotonin on cell level are immunoactive cells--neutrophils, eosinophils, leukocytes, monocytes and dendritic cells. Receptor and non-receptor described mechanisms of action of peripheral serotonin are described. immunoactive cells express on their membrane 5 HT1A-5-HT1E-5-HT2A-5-HT3-, 5-HT4- and 5-HT7-serotonin receptor subtypes. Activation of these receptors modulate the release of TNF-α, secretion of interleukins IL-1β, IL-6, IL-8/CXCL8, IL-12p40. Mediators of the non-receptor mechanisms are transporter SERT, tryptophan hydroxylase-1 and nuclear factor Nf-kB. Target-genes for Nf-kB are genes encoding cytokines. The cooperation of non/receptory pathways involved 5-HT1A- and 5-HT3 receptors. It is concluded that the diversity of ways of peripheral serotonin on the immune function of the body are existed.