As genetic tests for common gene variants and multifactorial, lifestyle-related conditions become available, it will be increasingly important to determine the psychological and behavioral impact of this emerging class of genetic tests. Our aim was to examine the potential impact of genetic testing for heart disease susceptibility on psychological predictors of smoking cessation. Two hundred and sixty-one smokers were asked to imagine that they had undergone a test for heart disease risk. They were randomly assigned to a genetic test scenario (low- or high-risk result) or an oxidative test scenario (high-risk result). Smokers in the genetic test-high risk group reported greater intention to quit smoking than smokers in the oxidative test-high risk group (p = 0.009); 30% of this was mediated by their holding stronger beliefs that quitting would reduce their heart disease risk (outcome expectations) (p = 0.011). The effect of genetic test-high risk feedback on outcome expectations was greatest amongst smokers with no heart disease family history (p = 0.038). The results suggest that genetic testing for heart disease risk may enhance interventions designed to improve health via increasing smoking cessation rates. Whether the findings hold true in studies that use real rather than hypothetical genetic tests remains to be seen.