Objective: To investigate the mid to long-term prognosis of medium or giant coronary aneurysms in children with Kawasaki disease (KD). Method: The clinical data of children with medium or giant coronary aneurysms due to KD were analyzed. Result: Forty four children with medium and giant coronary aneurysms were included. According to the AHA risk stratification of patients with KD, 11 were classified into risk level 3, 33 into risk level 4. The average follow-up period was 40.7±34.4 month. One child with giant aneurysms died of myocardial infarction 16 month after the acute phase. Another one with giant aneurysms had angina pectoris 14 years after the acute phase of KD. The remaining 42 patients had no clinical presentations of myocardial ischemia. ECG detected abnormal Q waves in 7, ST-T change in 3, and first A-V block in 1 girl. Around 87.3% of the medium-sized and 93.8% of the giant aneurysms located in LM, LAD, proximal RCA. About 58.4% of the aneurysms had the tendency to regress. Multiple logistic regression shows that the age of the onset, follow-up period and the initial size of the aneurysm are influencing factors of the regression of aneurysm(P<0.05. 64-slice spiral CT coronary angiogram have the advantage in detecting coronary artery calcification and lesions in distal-end of coronary artery. Conclusion: The mid to long term prognosis of children with medium or giant coronary aneurysms due to KD is probably better in this group of patients as compared to those reported from Japan.