Our study aimed to investigate the potential radioprotective effects of N-acetylcysteine (NAC) by comparing its biochemical effects with those of WR-2721, as a representative of clinically used radioprotectors, in preventing oxidative damage caused by gamma irradiation (single dose, 6Gy) in normal rat tissue. The rats (n=40) were divided randomly and equally into 4 groups:Control (C), Radiation (R), R+NAC (received irradiation and 1,000 mg/kg NAC) and R+WR-2721 (received irradiation and 200 mg/kg WR-2721) rats. Liver tissues and blood samples were harvested and utilized for reduced glutathione (GSH), malondialdehyde (MDA) and myeloperoxidase (MPO) detection. Serum and tissue GSH levels of R rats decreased compared to those of other groups (p<0.01). Tissue MDA levels of R+NAC and R+WR-2721 rats decreased compared to R rats (p<0.01; p<0.05, respectively). Tissue MPO activities of R+NAC and R+WR-2721 rats were higher than those of R rats (p<0.001). Serum MPO levels of R+WR-2721 rats were lower than those of C rats and R rats (p<0.01, p<0.001, respectively). In conclusion, the study suggests that the radioprotective effect against radiation-induced oxidative damage of NAC may be similar to that of WR-2721.