Abstract: Neighboring paraffin sections of pancreas of rat were performed with immunocytochemistry (PAP method and protein A gold-silver method).It was found that positive immunocytochemical reaction of Met-enkephalin and glucagon appeared in the same cells (I.e.A cell) of endocrine pancreas after a series of test for specificity of the reaction.According to some works reported previously,some other regulative neuropeptides exist in endocrine pancreas too,it could be concluded that the function of islet may be affected by a complicated neuro-humoral regulative system (including paracrine and autocrine regulation).The meaning of the coexistance of Met-enkephalin with other neuropeptides in the glucagon cell of Langerhan islet were discussed.