Objectives : Previously we reported that the roots of Panax ginseng C.A. Meyer (Araliaceae) increased sperm count and motility. also induced spermatogenesis via cAMP-responsive element modulator(CREM) activation in rat testes. In this study, for the first step of spermatogenesis in germ cell lines, the antioxidant activity of Panax ginseng were examined in mouse GC-1 spermatogonia cells. Methods : The extract was studied on diphenyl-picryl-hydrazyl (DPPH) radical scavenging activity, GC-1 cell viability by a modified MIT assay. H202-induced cytotoxicity by MIT assay and lipid peroxidation by malondialdehyde (MDA) formation. respectively. Results: The results showed that the extract scavenged DPPH radical with the IC50 being 0.631 mg/mi. The extract at concentrations of 5, and 10, 50, 100, 250 ${mu}$g/mi increased GC-1 cell viability significantly(p < 0.05, and p < O.O1). Hydrogen peroxide-induced cytotoxicity (73.8%, p < O.O1) was blocked by the extract at concentrations of 50, and 100, 250, 500 ${mu}$g/ml significantly (p < 0.05, and p < O.O1). The extract at concentrations of 10. and 50 ${mu}$g/ml decreased the MDA formation on hydrogen peroxide-induced lipid peroxidation. Conclusions : In conclusion, the extract of Panax ginseng has potent antioxidant activity and increases the survival rate of GC-1 spg cells against $H_20_2$-induced cytotoxicity.