Although some optimists may be accurate in their positive beliefs about the future, others may be unrealistic-their optimism is misplaced. Research shows that some smokers exhibit unrealistic optimism by underestimating their relative chances of experiencing disease. An important question is whether such unrealistic optimism is associated with risk-related attitudes and behavior. We addressed this question by investigating if one's perceived risk of developing lung cancer, over and above one's objective risk, predicted acceptance of myths and other beliefs about smoking. Hierarchical regressions showed that those individuals who were unrealistically optimistic (i.e., whose perceived risk was less than their objective risk) were more likely to endorse beliefs that there is no risk of lung cancer if one only smokes for a few years and that getting lung cancer depends on one's genes. Unrealistic optimists were also more likely to believe that a greater number of lung cancer patients are cured, but they were less likely to identify smoking cessation/avoidance as a way to reduce cancer risk. Most importantly, unrealistic optimists were less likely to plan on quitting smoking. Taken together, these data suggest that in the smoking arena, unrealistic optimism is a potentially costly cognitive strategy.