One of the national health objectives for 2010 is to reduce the prevalence of cigarette smoking among adults to < or =12% (objective no. 27-1a). To assess progress toward this objective, CDC analyzed self-reported data from the 2004 National Health Interview Survey (NHIS) sample adult core questionnaire. This report describes the results of that analysis, which indicated that, in 2004, approximately 20.9% of U.S. adults were current smokers. This prevalence is lower than the 21.6% prevalence among U.S. adults in 2003 and is significantly lower than the 22.5% prevalence among adults in 2002. The prevalence of heavy smoking (> or =25 cigarettes per day) has also declined during the past 11 years, from 19.1% of smokers in 1993 to 12.1% of smokers in 2004. Tobacco-use prevention and control measures appear to be decreasing both the prevalence of cigarette smoking and the proportion of heavy smokers, who are at high risk for tobacco-related morbidity and mortality. However, to further decrease smoking prevalence among adults and to meet the national health objective, effective comprehensive tobacco-control programs that address both initiation and cessation of smoking should be fully implemented in every state and territory.