The purpose of the present study was to investigate the effect of ethanol extracts from red pepper seeds on the antioxidative defense system and oxidative stress in rats fed a high fat high cholesterol diet. Rats were divided into four experimental groups which were composed of high fat high cholesterol diet group (HF), high fat high cholesterol diet with 0.1% ethanol extracts from red pepper seeds supplemented group (HEA), high fat high cholesterol diet with 0.2% ethanol extracts from red pepper seeds supplemented group (HEB) and high fat high cholesterol diet with 0.5% ethanol extracts from red pepper seeds supplemented group (HEC). Supplementation of ethanol extracts from red pepper seeds groups (HEA, HEB and HEC) resulted in significantly increased activities of hepatic glutathione peroxidase and catalase. Hepatic superoxide radical contents in microsome and mitochondria were significantly reduced in the groups supplemented with red pepper seeds ethanol extracts. Hepatic hydrogen peroxide content in the mitochondria was reduced in ethanol extracts from red pepper seeds supplemented groups. TBARS values in the liver were reduced in red pepper seeds ethanol extracts supplemented groups. Especially, HEB and HEC groups were significantly decreased compared to the HF group. Hepatic carbonyl values were significantly reduced in mitochondria in these supplemented groups. These results suggest that red pepper seeds ethanol extracts may reduce oxidative damage, by activation of antioxidative defense system in rats fed high fat high cholesterol diets.