Paraquat is a useful nonselective herbicide widely used throught the world. However accidental or intentional ingestion of the herbicide cause fatal pulmonary injuring. But there is not suitable antidote of paraquat intoxication and therapeutic agents now be used are not effective. So, in this study we intended to evaluate the inhibitory effects of acetylmannan from Dioscorea batalas on paraquat toxicity. 100mg/kg acetylmannan from wild or cultured Dioscorea bataras was administered orally to male SD rats for 3 days and the administration time interval was 24hours. After one hour of final administration, 50mg/kg paraquat was administered intraperitonially. After 24 hours, the biochemical parameters of blood and tissues were examined. In paraquat treated groups, sGPT, BUN, creatinine, ALP levels were increased by 2 to 4 times of normal values. However in acetylmannan from wild Dioscorea batatas treated groups, sGPT, BUN, creatinine, ALP levels in blood and lung tissue were significantly decreased to normal levels. In acetylmannan from cultured Dioscorea batatas treated groups, BUN, creatinine were significantly decreased to normal values, but not in sGPT, ALP levels. Therefore, we concluded that acetylmannan from wild Dioscorea batatas can be used as an. antidote of paraquat toxicity.