Severe coronary artery lesions (CALs) in affected children with Kawasaki disease (KD) usually need further assessment and coronary artery bypass grafting. Six cases were recruited in this report, including 4 boys and 2 girls, aged 12m, 3y6m, 4y6m, 7y4m, 8y, 10y4m respectively. CALs were found by echocardiography (ECHO) during the 15th to 21th day of the course. All patients were followed up with ECHO and ECG regularly, among whom 2 had angina and 3 had heart failure. Five patients had ST-T changes in ECG. In addition to multiple coronary aneurysms, ECHO also showed enlargement of left atrium and left ventricle with low ejection fraction and shortening fraction in 3 patients, and ventricular wall movement disconcordance in 2 patients. The remaining one had multiple ischemic focus in 99mTc-MIBI. Coronary artery angiography was performed in all patients from 6 months to 65 months after diagnosis of KD, and showed more than one coronary aneurysm formation and at least one aneurysm was giant in all patients, with thrombogenesis and distal coronary artery blocked in 5 patients. All patients underwent coronary artery bypass grafting and giant coronary aneurysm size-reducing repair. Five patients had satisfactory immediate results. However, the 22-month-old girl died in the operation. During follow-up, LVEF gradually improved, but not to normal. In conclusion, CALs should be followed up in patients with KD regularly. ECG, ECHO and 99mTc-MIBI and even MSCT if available should be combined for examination in those severe cases. CABG should be considered when myocardial ischemia was detected.