Background: The long-term outcome of Systemic artery aneurysms (SAA) caused by Kawasaki disease (KD) remains unknown. SAA refers to aneurysms developing anywhere in the arterial system other than the coronary circulation. SAA included peripheral artery aneurysm (PAN) and aortic artery aneurysm. Methods: We investigated the characteristics and the fate of SAA in 20 patients (14 males and 6 females) from their medical records and angiograms. The onset age of KD ranged from 1 to 20 months with a median of 6 months. The interval from the onset of KD to the latest angiogram ranged from 16 months to 24 years (median 18 years). The residual rate of PAN and the incidence of stenotic lesions were analyzed by the Kaplan-Meier method in 11 pts, who had undergone initial angiograms within 4 months. Results: The mean duration of fever was 24±12 days. All 20 patients had at least a symmetric pair of aneurysms in bilateral peripheral arteries and 16 pts (80%) had multiple PAN. The number of respective SAA was as follows, brachial artery 32, common iliac artery 20, internal iliac artery 21, abdominal aortic aneurysm 7, and others 30. The residual rates of PAN at 10 and 20 years after the onset of KD were 66% and 51%, respectively (n=42). The incidence of stenotic lesions at 10 and 20 years after the onset of KD was 6 % and 25 %, respectively. The diameter of PAN in the acute phase leading to stenotic lesions in the late period was more than 10.0mm. Conclusions: PAN occurred symmetrically and were multiple in younger infants and those with severe acute vasculitis. The fate of PAN resembles that of coronary artery aneurysms, and depends on its acute phase diameter. The larger PAN can lead to stenotic lesions in the late period.