Paraquat (1,1 '-dimethyl-4,4'-bipyridylium dichloride) is widely used as a herbicide. Accidental or intentional ingestion of paraquat is common in many developing countries such as China, Sri Lanka and Korea because of easy access. The high mortality rate of paraquat is due to its high toxicity and the lack of effective treatments. Thus, the paraquat poisoning becomes one of major medical problem in the developing countries.