In this report, the oxidation of biomembrane lipids, phospholipid and cholesterol (ChH), was examined experimentally in the presence of vitamin E (V H) by using a liposome system, which is widely used as a biomembrane model. A kinetic model was constructed by taking into account mechanisms of antioxidation and pro-oxidation by V H and the co-oxidation mechanisms of biomembrane lipids reported previously. The model quantitatively described oxidation behavior in the liposome system under various V H addition conditions. The model also predicted oxidation behavior in vivo under various oral ingestion conditions of V H. The results suggest that ChH oxidation, which causes various diseases, can be suppressed effectively by taking a certain amount of V H once a day to avoid a reduction in the V H concentration present in the biomembrane. The proposed kinetic approach should be a useful tool for quantitatively characterizing complicated reaction systems, such as biomembrane oxidation. E E E E E E