Objective：To evaluate the effect of cigarette smoking on washout time after one minimum alveolar concentration of sevoflurane anesthesia for one hour. Methods：We investigated the washout time of sevoflurane in 45 non-smoking and 45 cigarette smoking (≥10 cigarettes/day for>5 years) ASA I-II physical status patients, aged 20-63 years, who were candidates for LC surgery under 1MAC standardized sevoflurane anesthesia for one hour. After one hour the sevoflurane vaporizer was turned off and the time taken for the sevoflurane concentration to decrease to 0.3MAC and 0.1 MAC levels were recorded. The patients were mechanically ventilated during the washout time. Results: We found the difference between the two study groups with regard to washout time of sevoflurane. The times of 1MAC down to 0.3MAC (117±38 sec in non-smokers vs 99±42 sec in smokers, p>0.05) were similar, but the times of 1MAC down to 0.1MAC (501±176 sec in non-smokers vs 411±140 sec in smokers, p<0.05) were different. Conclusion：Washout time of 1MAC sevoflurane anesthesia for one hour is effected by cigarette smoking in patients without significant pulmonary disease.