The effect of dietary red bell pepper (Capsicum annuum L.) on learning performance was studied in the senescence-accelerated mouse (SAM). An experimental diet, which contained 20% (w/w) lyophilized powder of red bell pepper, was fed to SAMP8 mice. The mice that received the experimental diet showed much better acquisition in passive avoidance tasks as compared with a control group given a common diet. This indicated that the dietary ingestion of red bell pepper ameliorated the learning impairment in SAMP8.