The protective effects of total flavonoids from Lycium Barbarum L. (TFL) on lipid peroxidation in mitochondria and red blood cells (RBC) induced by oxygen radicals produced by Fe2+ cysteine system were investigated. The mitochondria lipid peroxidation (measured as malondialdehyde, MDA) was significantly inhibited by TFL with a dose-response relation between the concentrations of 0.025 and 2.0 mg/ml, and the fluidity of mitochondria membrane was also protected effectively. It was observed by scan electron microscope, that the shape of RBC in the Fe2+ system was damaged significantly. The shape of RBC was remained with the addition of TFL.