The jejuna and kidneys were randomly taken from 6 SD rats(Rattus norvegicus)and 7 Kunming mice (Mus musculus). The expression of ATP7B and PCNA was observed by immunohistochemistry technique,and the relevance of ATP7B and PCNA expression was analyzed. The results showed that,in both rat and mouse, ATP7B was mainly expressed in small intestinal glands,striated border,near-cavity surface and near-basement surface of intestinal epithelial cells,as well as renal tubule and collecting duct. PCNA was strongly expressed in small intestine glands and the connective tissues. In kidney,PCNA was expressed in a few cells of renal tubule, collecting duct and glomerulus. Although both ATP7B and PCNA were expressed in the jejunum and kidney in both species,there was no significant correlation between integral optical density of ATP7B and PCNA immunoreactive positive substances (P > 0.05). In jejunum and kidney,the expression of ATP7B had no relationship with the level of cell proliferation.