Nicotine is a liquid alkaloid present in tobacco leaves at a 1~6% concentration. Green tobacco sickness is an occupational illness caused by absorption of nicotine through skin exposed to wet tobacco leaves. It occurs throughout the world in tobacco-growing areas. The almost universal symptoms of weakness, nausea, vomiting, diarrhea, and dizziness may be confused with pesticide poisoning or heat stress illness. Since its recognition in the 1970s, green tobacco sickness is self-limited, usually lasting 1 to 2 days. There is no antidote, so treatment is supportive (for example, intravenous fluids for hypotension, antiemetics). The diagnosis can beconfirmed by measuring the nicotine concentration in the serum or urine, but its half-life is only 3~4 hours. Cotinine, the major nicotine metabolite, has a half-life of 36 hours, and thus is more useful. Young workers may be at higher risk for green tobacco sickness. Tobacco use is thought to offer weak protection by inducing tolerance. Handling tobacco that is wet from rain or dew increase the risk of green tobacco sickness. Repeated daily exposure over more than a week may also increase the risk. Green tobacco sickness is preventable by use of protective clothing and by avoiding skin contact with wet tobacco. When clothing becomes wet from environmental dampness or sweating, it should be changed to maintain an effective barrier. The best treatment is avoidance of poisoning : in addition to wearing gloves, long pants and a full shirt, workers picking or handling tobacco leaves should clean their hands frequently.