We investigated the effect of maslinic acid (a triterpene derivative obtained from olive pomace), on the susceptibility of plasma or hepatocyte membranes to lipid peroxidation (LPO), induced respectively by the hydroxyl radical (OH*) generated by Fe2+/H2O2 ex vivo and by the system Fe3+/ascorbate in vitro; moreover, three groups of animals used in the plasma study were pretreated with CCl4 (to generate CCl3-*). Endogenous plasma lipoperoxide levels and susceptibility to LPO were decreased in rats treated with maslinic acid, after exposure to OH* by Fe2+/H2O2 (Fenton reaction). Co-incubation with maslinic acid prevented hepatocyte membrane LPO as shown by the reduction of TBARS. In conclusion, maslinic acid may offer some advantages in the resistance of oxidative stress in the animals.