AIM: To investigate the efficacy of N-acetylcysteine (NAC) and Taurine (Tau) in preventing hyperoxia-induced the lens opacification and the changes of biochemical parameters on organ cultured rabbit lenses. METHODS: Twenty-four lenses from adult rabbits were divided into the control group, the hyperoxia-exposed group, the hyperoxia-exposed group containing 20mmol/L of NAC, the hyperoxia-exposed group containing 80mmol/L of Tau, respectively. The treated groups incubated with hyperoxia (PO² >80%) for 4 hours per day throughout a 7-day period. Lens transparency, histology and enzymatic activities measurements were determined after this incubation. RESULTS: Gross morphological examination of these lenses revealed some severe cortical opacification in the hyperoxia-exposed group, moderate cortical opacification in the control group and the Tau treated group. There was minimal cortical opacification in the NAC treated group. The glutathione (GSH) content and the activity of Na, K-ATPase were significantly decreased in the hyperoxia-exposed group than that of the control group, by 37.8% ( P<0.05) and 53.5% ( P<0.05), respectively. However, they were increased in the two treated groups, especially in the NAC treated group. There were no significant differences in the water-soluble protein content and the catalase and GSH reductase activities in all group lenses. CONCLUSION: Hyperoxia can induce the cortical opacification in the lens. The role of NAC in the prevention of hyperoxia-induced cataract is superior to Tau.