Cigarette excise tax changes ultimately influence the health of smokers and potential smokers. An 8-cent decrease in the federal tax is estimated to induce up to 1 million young persons, ages 12 to 25 years, to smoke, when without the tax decrease they would not. Hundreds of thousands of Americans older than 25 years would also start or continue smoking as a result of the tax decrease. Conversely, an 8- to 16-cent tax increase would encourage from 1 to 2 million young persons and 800,000 to 1.5 million adults to quit smoking or not to start. Thus, a tax increase could prevent hundreds of thousands of premature smoking-related deaths, while a tax decrease would contribute to the disease burden of tobacco. Intentionally or inadvertently, the federal cigarette excise tax is a powerful tool of public health policy.