We evaluated the effect of cabergoline on superoxide anion production by rat microglial cells using a 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1, 2-a]pyrazin-3-one-dependent chemiluminescence assay. Cabergoline dose-dependently inhibited superoxide anion production by microglial cells stimulated with phorbol myristate acetate or opsonized zymosan, while it had no superoxide dismutase-like activity. We also studied the effects of cabergoline and α-tocopherol on thiobarbituric acid reactive substances formation in homogenized brain-tissue in rats. Cabergoline was stronger than α-tocopherol in inhibiting auto-oxidation. While cabergoline is commonly used to treat the motor dysfunction of Parkinson's disease, it may also be effective in inhibiting oxidative stress, a possible mechanism of dopaminergic neuronal degeneration in Parkinson's disease.