Healthcare providers' ability to motivate people to try to quit smoking or to remain abstinent is limited. Even with our best treatments, most smokers relapse within 1 year. Therefore it is important that we constantly strive to develop and test new, effective smoking interventions. Providing feedback on one's biomarkers (e.g., biological indices of smoking-related harm, harm exposure, or genetic susceptibility to disease) have been suggested as potentially useful for increasing smokers' motivation or ability to quit smoking. In fact, variations of this strategy are commonly incorporated into behavioral smoking-cessation interventions, but little empirical evidence has specifically addressed whether this approach is effective. In this article, the author reviews the theoretical rationale and empirical evidence regarding this practice. Although the preliminary evidence is promising, more research is needed to determine the efficacy of using biomarkers and the limits of the strategy's effectiveness. Future investigations should address these issues.