In the absence of the antismoking campaign, adult per capita cigarette consumption in 1987 would have been an estimated 79-89 per cent higher than the level actually experienced. The smoking prevalence of all birth cohorts of men and women born during this century is well below that which would have been expected in the absence of the campaign. As a consequence, in 1985 an estimated 56 million Americans were smokers; without the campaign, an estimated 91 million would have been smokers. As a result of campaign-induced decisions not to smoke, between 1964 and 1985 an estimated 789,200 Americans avoided or postponed smoking-related deaths and gained an average of 21 additional years of life expectancy each; collectively this represents more than 16 million person-years of additional life. The greatest health benefit lies in the future, however, as younger individuals reach the ages at which smoking claims its greatest toll, and as middle-aged former smokers realize relative reductions in smoking mortality risks as a result of long-term abstinence from smoking. For example, campaign-induced decisions not to smoke made prior to 1986 will result in the postponement or avoidance of an estimated 2.1 million smoking-related deaths between 1986 and the year 2000.