Introduction. At present, signaling pathways involved in the development of innate and adaptive immune responses and comprising, inter alia, the interaction of pattern-recognizing receptors, such as TLR, with antimicrobial peptides associated with inflammation, proliferation, production of cytokines and chemokines, are actively studied. Among them, there is f-defensin, the localization of which in rat colon tissue and expression changes under bacterial endotoxemia are still poorly understood. At the same time, an important problem in the study of neuroimmune interactions is to reveal potential relationships between the production of endogenous defensins and TLR expression, in particular, by enteric neurons. The aim of the study. In the present study, we investigated the localization of f-defensin-1 (rBD1) in rat colon tissue under normal conditions and on the model of bacterial endotoxemia induced by Escherichia coli lipopolysaccharide (LPS). Results. By means of immunohistochemistry, we have shown rBD1 to be