This monograph, the fifth in the NCI Smoking and Tobacco Control series, provides important information for clinicians interested in reducing the tremendous burden of disease caused by cigarettes and other tobacco products. As health professionals we can and must contribute to this effort, both by assisting individual patient cessation and by contributing to broader tobacco control activities in our communities. Cigarette smoking is still this Nation's largest cause of premature death and disability and remains the only product that, when used as intended by the manufacturer, will kill the consumer. Every physician and dentist can and should become a smoking expert to counter the pervasive attempts by the tobacco industry to convince smokers and would-be smokers that smoking is desirable, sexy, or fun. We need to remind ourselves that for decades the cigarette industry blatantly used the medical profession in cigarette advertising and enticed entire generations into believing that smoking was safe. Even today, 30 years after it became known with overwhelming scientific certainty that smoking was a major health threat, cigarette advertisers still portray smoking as free from any significant health risk. Health professionals have been an integral part of the national effort to reduce smoking in the United States, and in fact, the first major smoking information campaign launched by the U.S. Public Health Service was based on changes in physicians' smoking behavior. However, we must do more.