Smokers smoke in large part because of the addictive effects of nicotine. Nicotine affects mood and performance and has been clearly implicated as the source of addiction to tobacco. People smoke to deliver desired doses of nicotine to their bodies, with certain rates of delivery and intervals between doses; these behaviors tend to be consistent for a person from day to day. Rational treatment of the pharmacologic aspects of tobacco addiction includes nicotine substitution therapy. New formulations of nicotine substitutes will provide more options to the physician for tailoring treatment to the needs of individual smokers. Other pharmacotherapies, particularly antidepressant drugs, hold promise for certain smokers.