Nearly a decade after the identification of the Alzheimer amyloid precursor protein (APP) gene several groups of investigators have created transgenic mice expressing APP that simulate some of the prominent behavioral and pathological features of Alzheimer's disease (Quon et al., 1991; Games et al., 1995; Hsiao et al., 1995, 1996; Moechars et al., 1996; Sturchler-Pierrat et al., 1997). These features, which are present to various degrees in different lines of mice, include age-related impairment in learning and memory, neuronal loss, gliosis, neuritic changes, amyloid deposition, and abnormal tau phosphorylation. No mouse model exhibiting every neuropathological feature of Alzheimer's disease exists. Whether an exact simulation of Alzheimer neuropathology is required to understand neural dysfunction in Alzheimer's disease is unclear. Various mouse models of Alzheimer's disease are summarized in this article.