Two studies were conducted to investigate unrealistic optimism among adolescent cigarette smokers. In the first study, 54 smokers and 304 nonsmokers agreed that there was a strong relationship between smoking and lung cancer. Nonsmokers accurately perceived their chances of contracting lung cancer as below average. However, smokers perceived themselves as having only an average chance of contracting lung cancer. The second study replicated the first in both procedure and results regarding lung cancer, but also added perceptions of the relationship between smoking and two other smoking-related health problems, emphysema and heart attacks. The results were similar: 33 smokers rated their chances of developing emphysema and having heart attacks as higher than 299 nonsmokers, but still viewed their chances as only about average. Finally, perceptions of stress were examined. Smokers perceived themselves to be under more stress than nonsmokers. It was concluded that self-deception as indicated by unrealistic optimism regarding the chances of getting smoking-related diseases characterized adolescent smokers.