Background: Percutaneous coronary intervention (PCI) is commonly performed in patients with stable coronary artery disease, despite current evidence suggesting that such patients derive minimal benefit from the procedure. We sought to determine the influences on cardiologists' decision to perform elective PCI in patients with stable coronary artery disease. Methods: We conducted a qualitative study using 3 focus groups of interventional and noninterventional cardiologists in California. Participants discussed issues surrounding the decision to perform PCI using hypothetical case scenarios. We analyzed the data according to the principles of grounded theory. Results: Despite acknowledging data showing that PCI offers no reduction in the risk of death or myocardial infarction in patients with stable coronary artery disease, cardiologists generally believed that PCI would benefit such patients. Reasons given for performing PCI included belief in the benefits of treating ischemia and the open artery hypothesis, especially with drug-eluting stents; potential regret for not intervening if a cardiac event could be averted; alleviation of patient anxiety; and medicolegal considerations. Participants believed that, in patients undergoing coronary angiography, an "oculostenotic reflex" prevailed and all significant amenable stenoses would receive intervention, even in asymptomatic patients. Conclusions: The widespread application of PCI in stable coronary artery disease for indications unsupported by evidence may reflect discordance between cardiologists' clinical knowledge and their beliefs about the benefits of PCI. Nonclinical factors appear to have substantial influence on physician decision making. Future studies should focus on the development of methods to help providers more fully incorporate clinical evidence into their medical decision making.