Quetiapine, an atypical antipsychotic drug, may have beneficial effects in Alzheimer's disease (AD), and the effect of quetiapine on object recognition memory in AD has never been measured. The aim of the present study was to evaluate the effects of quetiapine on object recognition memory and on oxidative stress that could be involved in the AD pathogenesis in an amyloid precursor protein/presenilin-1 double transgenic mouse model of AD. Nontransgenic and transgenic mice were treated with quetiapine (0 or 5 mg/kg/day) in drinking water from the age of 2 months. After 10 months of continuous quetiapine administration, object recognition memory impairment and the increased hippocampal protein expression of nitrotyrosine, a protein marker of oxidative stress, were attenuated in the AD mice. These results suggest that quetiapine can attenuate object recognition memory impairment and brain oxidative stress in an amyloid precursor protein/presenilin-1 transgenic mouse model of AD and indicate that the antioxidative effect of early quetiapine intervention may be associated with the beneficial effect of quetiapine on memory in AD.