Abstract: Objective To study the protective effect and mechanism of lipoic acid(LA)on oxidative damage of rat brain homo genate induced by H₂O₂.Methods Fresh rat brain homogenates were divided into LA group and LA+H₂O₂ group.The rat brain homogenate of LA groups was treated with 0,100,200 and 300 mol/L LA and the rat brain homogenate of LA+H₂O₂ grous was treated with 100 mol/L H₂O₂ and 0,100,200 and 300 mol/L LA,respectively.The treatment time was one hour.The levels of MDA and GSH were measured.Results 100 mol/L H₂O₂ increased the level of MDA to 11.85±0.83 mol/(g·pro).The levels of GSH was decreased to 21.21±4.91 mol/(g·pro)compared with that of the control(P<0.05).1 00-300 mol/L LA could decreased the level of MDA from 20.2 to 28.1 percent.The level of GSH increased from 50.1 to 63.3 percent compared with 100 mol/L H₂O₂ group with significant difference(P<0.05).Conclusion Acerta in level of LA can inhibit significantly the oxidative damage of rat brain homogenate induced by H₂O₂.Its mechanismmay be the increase of GSH level and decrease of MDA level through the role of elevation GSH level.