Background Up to 25% of patients with untreated Kawasaki Disease (KD) and 5% of those treated with intravenous immunoglobulin will develop coronary artery aneurysms. Persistent aneurysms may remain silent until later in life when myocardial ischemia can occur. We sought to determine the prevalence of coronary artery aneurysms suggesting a history of KD among young adults undergoing coronary angiography for evaluation of possible myocardial ischemia. Methods and Results We reviewed the medical history and coronary angiograms of all adults under age 40 who underwent coronary angiography for evaluation of suspected myocardial ischemia at four San Diego hospitals from 2005–2009 (n=261). History of KD-compatible illness and cardiac risk factors (RF’s) were obtained by medical record review. Angiograms were independently reviewed for the presence, size, and location of aneurysms and CAD by two cardiologists blinded to the history. Patients were evaluated for number of RF’s, angiographic appearance of their coronary arteries, and known history of KD. Of the 261 young adults who underwent angiography, 16 had coronary aneurysms. After all clinical criteria were assessed, 5.0% had aneurysms definitely (n=4) or presumed (n=9) secondary to KD as the etiology of their coronary disease. Conclusions Coronary sequelae of KD are present in 5% of young adults evaluated by angiography for myocardial ischemia. Cardiologists should be aware of this special subset of patients who may benefit from medical and invasive management strategies that differ from the treatment of atherosclerotic CAD.