Mitochondrial dysfunction has been implicated in causing metabolic abnormalities in Alzheimers disease (AD). The searches for mitochondrial DNA variants associated with AD susceptibility have generated conflicting results. The age-related accumulation of somatic mitochondrial DNA deletion has been suggested to play a pathogenic role in the development of AD. Recent studies have demonstrated that amyloid-beta peptide (Aβ) progressively accumulates in mitochndrial matrix, as demonstrated in both transgenic mice over-expressing mutant amyloid precursor protein (APP) and autopsy brain from AD patients. Aβ-mediated mitochondrial stress was evidenced by impaired oxygen consumption and decreased respiratory chain complexes III and IV activities in brains from AD patients and AD-type transgenic mouse model. Furthermore, our studies indicated that interaction of intramitochondrial Aβ with a mitochondrial enzyme, amyloid binding alcohol dehydrogenase (ABAD), inhibits its enzyme activity, enhances generation of reactive oxygen species (ROS), impairs energy metabolism, and exaggerates Aβ-induced spatial learning/memory deficits and neuropathological changes in transgenic AD-type mouse model. Interception of ABAD-Aβ interaction may be a potential therapeutic strategy for Alzheimers disease.