The activities of glutathione peroxidase, superoxide dismutase, and catalase reduced in the supernatant of the hippocampus and cerebral cortex of rats with AlCl3-induced AD (P<0.05), and the MDA content increased in the supernatant of the hippocampus and cerebral cortex and the erythrocytes of the jugular blood of rats with AlCl3-induced AD. This evidence concerns the gene CAT and Alzheimer disease.