Purpose To observe the histopathologic changes of acquired immure deficiency syndrome (AIDS) in a Chinese Rhesus monkeys model and the pathogenesis that initiated the changes.Methods Chinese Rhesus monkeys were sacrificed after being inoculated SIVmac239 by Ⅳ(n=2)for four months.Autopsy was carried out by pathologic routine method.The lymph nodes, heart, liver, spleen, lung, kidney, digestive tract and other tissues were selected, the tissues fixed with 10% neutral formalin, and the pathologic sections were prepared by HE staining and immunohistochemical staining and special staining after paraffin imbedding.Results The main histopathological changes appeared in the immune system in different organs. The lymph nodes began to display the complex changes in a short period of time infected by the virus, including proliferation of lymphoid follicles, atrophy, or both; some lymphoid follicles of lymph nodes had few lymphocytes, with fibrous hyperplasia and immune complex (IC) deposition, displaying a burning down phenomenon.Splenomegaly and blood vessel and its endothelial cell proliferation in splenic corpuscles were noted with the immune complex deposition. Other parts of the mucosa-associated lymphoid tissue had different degrees of hyperplasia, or atrophy.Conclusion Histopathologic changes in Chinese Rhesus monkeys infected by SIVmac239 strain are very similar to human AIDS, which suggests that the model is a useful tool for the prevention and treatment study of AIDS.