Abstract: To observe the localization of neurokinin receptor (NK3r) in the mouse gastrointestinal tract.Immunohistochemistry and immunoreactive fluorescence were used in the experiment.Our results showed that there arent NK3r-like (-Li) positive materials on the smooth muscle cells of oesophagus,stomach,and intest ine and other regions muscularis.The nerve cell bodies with immunoreactivity for NK3r mainly distributed in the submucous nerve plexus or myenteric nerve plexus of gastrointestinal tract except oesophagus and stomach and rectum.The reaction production was distributed on the nerve cell surfaces.Occasionally was observed in the cell plasma,but was very weak stained.Immunoreactive nerve cells morphology was mostly like type of Dogiel Ⅱ.This research work not only described the distribution of neuronkinin B receptor in the mouse gut in detail,but also provided a morphological basis for deducing the functional identity of NK3r-immunoreactivity nerve cells in the gut.