Female and male mentholated cigarette smokers, aged 18 to 30 years; history of smoking for the past 12 months, at least one cigarette per day; smoking status is verified with urinary cotinine levels above 10 ng/ml; not seeking treatment for nicotine dependence at the time of study entry in good health as verified by medical history, screening examination, and screening laboratory tests; for women, not pregnant as determined by pregnancy screening, nor breast feeding, and using acceptable birth control methods.