Background. Kawasaki disease is an acute vasculitis syndrome of unknown etiology that mainly affects the coronary arteries. The purpose of this study was to assess the agreement between dipyridamole stress technetium 99m sestamibi single photon emission computed tomography (SPECT) and coronary angiography in these patients. Methods and Results. Forty-one consecutive patients (29 boys and 12 girls) who underwent coronary angiography were studied prospectively. Their ages at onset of the disease ranged from 2 months to 4.8 years (mean+/-SD, 1.9+/-1.3 years). Their ages at the time of the study ranged from 8 months to 15.3 years (6.2+/-4.4 years). The duration between symptom onset and the study ranged from 2 months to 12 years (4.3+/-4.0 years). All patients underwent dipyridamole stress Tc-99m sestamibi SPECT within 1 month of their angiographic studies. They were divided into 3 groups according to coronary angiography findings. Group A consisted of 2 patients (I boy and 1 girl, aged 10.3 and 1.9 years, respectively) with coronary stenoses who also had aneurysms. Group B consisted of 10 patients (8 boys and 2 girls, aged 0.7-15.3 years [mean, 3.8 years]) with coronary aneurysms. Group C consisted of 29 patients (20 boys and 9 girls, aged 1.2-13.8 years [mean, 7 years]) with normal coronary angiograms. Two patients in group A (100%), 3 of 10 patients in group B (30%), and 19 of 29 patients in group C (65.5%) had myocardial perfusion defects. There was poor agreement between Tc-99m sestamibi SPECT and coronary angiography for detecting coronary stenoses (kappa=0.07; P=.222) and aneurysms (kappa=-0.184; P=.158). Conclusion. Significant discordance exists between Tc-99m sestamibi SPECT and coronary angiography in patients with Kawasaki disease.