We examined antioxidant activity of cabergoline, a dopamine agonist, during the aerobic oxidation of phosphatidylcholine liposomes at 37°C. Cabergoline retarded the oxidation initiated with a lipid-soluble initiator significantly better than that with a water-soluble initiator, suggesting that cabergoline locates in the lipid layer of liposomal membranes. Cabergoline inhibited the oxidation of liposomal membranes synergistically with endogenous antioxidants such as ascorbic acid, ubiquinol-10 and vitamin E, and vitamin E was the most efficient synergist. These results suggest that cabergoline may have a neuroprotective effect on the substantia nigra of Parkinsonian patients because of its synergistic antioxidant activity with vitamin E as well as its action on dopamine receptor.