Current treatments for patients with coronary aneurysms caused by Kawasaki disease (KD) are based primarily on aneurysm size. This ignores hemodynamic factors influencing myocardial ischemic risk. We performed patient-specific computational hemodynamics simulations for 15 KD patients, with parameters tuned to patients’ arterial pressure and cardiac function. Ischemic risk was evaluated in 153 coronary arteries from simulated fractional flow reserve (FFR), wall shear stress, and residence time. FFR correlated weakly with aneurysm -scores (correlation coefficient, ) but correlated better with the ratio of maximum-to-minimum aneurysmal lumen diameter (). FFR dropped more rapidly distal to aneurysms, and this correlated more with the lumen diameter ratio () than -score (). Wall shear stress correlated better with the diameter ratio (), while residence time correlated more with -score (). Overall, the maximum-to-minimum diameter ratio predicted ischemic risk better than -score. Although FFR immediately distal to aneurysms was nonsignificant, its rapid rate of decrease suggests elevated risk.