This study reports consumer reactions to the graphic health warnings selected by the Food and Drug Administration to be placed on cigarette packs in the United States. We recruited three sets of respondents for an experimental study from a national opt-in e-mail list sample: (i) current smokers aged 25 or older, (ii) young adult smokers aged 18-24 and (iii) youth aged 13-17 who are current smokers or who may be susceptible to initiation of smoking. Participants were randomly assigned to be exposed to a pack of cigarettes with one of nine graphic health warnings or with a text-only warning statement. All three age groups had overall strong negative emotional (ß = 4.7, P < 0.001 for adults; ß = 4.6, P < 0.001 for young adults and ß = 4.0, P < 0.001 for youth) and cognitive (ß = 2.4, P < 0.001 for adults; ß = 3.0, P < 0.001 for young adults and ß = 4.6, P < 0.001 for youth) reactions to the proposed labels. The strong negative emotional and cognitive reactions following a single exposure to the graphic health warnings suggest that, with repeated exposures over time, graphic health warnings may influence smokers' beliefs, intentions and behaviors.