Abstract: Action of N-acetyl-L-cystein (NAC) for resisting damage of human skin fibroblast (HSF) induced by H₂O₂ was studied.Results of experiments for cell survival ratio and cell positive ratio showed that under low mass concentration (50－100 mg·L^-1) of NAC,there is no obvious cell toxicity;and under mass concentration of 200~800 mg·L^-1,cell proliferation is promoted;while under higher mass concentration (1 000 mg·L^-1),the growth of HSF is inhibited obviously.Positive ratio of blank group,H₂O₂ group,H₂O₂ (500 μmol·L^-1)+NAC (100 mg·L^-1) group and H₂O₂ (500 μmol·L^-1)+NAC (200 mg·L^-1) group is 39.90%,69.57%,45.29% and 36.60% respectively.NAC can decrease the cell positive ratio obviously and resist the cell damage induced by H₂O₂.

Key words: additive of cosmetics, N-acetyl-L-cystein, human skin fibroblast, toxicity, damage