Objective To observe changes of peripheral immune function in patients with Alzheimer’s disease and to investigate their clinical meanings. Methods A total of 48 cases in Guangzhou Welfare Center from June 2006 to April 2007 were consecutively selected as the observed subjects, including 19 mild to moderately severe AD patients, 10 severe AD patients and 19 healthy age-matched controls.Level of the anti-β-amyloid peptide antibody was detected by ELISA. Distribution of the T, B-cell subsets was determined by flow cytometry (FACS). The production of IFN-γ and IL-4 by peripheral blood mononuclear cell(PBMC) after stimulation with 1-42 beta-amyloid (Aβ) fragments was also evaluated by ELISA and ELISPOT. Results Compared to the controls, the levels of AβSUB>42/SUB>antibody in serum in the patients with different course of AD were significant decreased (EM>P/EM><0.05 and EM>P/EM><0.01, respectively). The levels of CDSUB>8/SUB> in peripheral blood from patients with different degree of AD were upregulated to some extent（EM>P/EM><0.05)；In conurast, CDSUB>4/SUB> were significant downregulated（EM>P/EM><0.05）；After stimulated with antigen AβSUB>42/SUB>, the level of IFN-γ in the cultured medium of PBMC in HC was significant higher than that in both AD groups （EM>P/EM><0.05）. After stimulated with antigen AβSUB>42/SUB>, in every 4