Abstract: AIMTo investigate the role of ginsenoside Rg1 in preventing against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced apoptosis of the substantia nigra neurons in the mouse model of Parkinson′s disease (PD). METHODSC57Bl male mice were given MPTP ip in the PD model group. Different doses of ginsenoside Rg1 (2.5, 5.0 and 10.0 mg·kg^-1) were given ip 3 days prior to MPTP in the pretreatment group. Nissl staining, tyrosine hydroxylase (TH) immunostaining and TdT-mediated dUTP nick-end labeling (TUNEL) staining were used to observe the damage of nigral neurons. The method of immunostaining was used to detect the caspase-3 activity, expression of inducible nitric oxide synthase (iNOS) and neuronal nitric oxide synthase (nNOS). RESULTSPretreatment with ginsenoside Rg1 was shown to prevent the loss of Nissl staining neurons and TH-positive neurons, and decrease the percent of TUNEL-positive. Simultaneously, Rg1 was found to reduce caspase-3 activity and the expression of iNOS. CONCLUSIONGinsenoside Rg1 showed protective effect on MPTP-induced apoptosis in the mouse nigral neurons and this effect may be attributable to reducing the expression of iNOS and inhibiting the activation of caspase-3.