Oxidative stress-induced dopaminergic neurons toxicity is a key pathogenic factor of Parkinson’s disease.Protecting dopaminergic neurons from oxidants induced damage is beneficial to the treatment of PD.Carnosic acid (CA) has been reported to exhibit excellent anti-oxidative activity.In the present study,we investigated the protective effect of CA on MPTP induced culture dopaminergic neurons toxicity.Studies showed that pretreatment with CA could effectively reverse MPTP induced the atrophy of dopaminergic neuron and neuronal viability decrease.Moreover,CA pretreatment effectively reversed MPTP induced LDH,MDA,caspase 3 mRNA and protein increase and SOD decrease.The result demonstrated that the administration of CA protected against MPTP induced dopaminergic neurons toxicity and the mechanisms may be related to the protection of oxidative damage and prevention of abnormal caspase-3 increase.