Background Ongoing low-grade inflammation and endothelial dysfunction persist in patients late after Kawasaki disease (KD). Statins not only reduce cholesterol, but also improve surrogate markers of atherosclerosis and endothelial dysfunction, but their effects for children late after KD complicated with coronary arterial abnormality (CAA) has not been evaluated. Methods and Results The 11 KD children complicated with CAA (mean age 12.9±2.5 years, mean interval from episode 10.77±3.01 years) and 11 age- and gender-matched healthy controls were studied. The KD group received oral simvastatin 10 mg/day for 3 months. Lipid profiles, high-sensitivity C-reactive protein (hs-CRP) and flow-mediated dilation (FMD) of the brachial artery were performed at baseline in both groups and 3 months later in the KD group. At baseline, the KD group had significantly higher hs-CRP level and decreased FMD than the control group. After 3 months' treatment, the KD group showed a significant reduction in the hs-CRP level and a significant increase in FMD. Conclusions In this small study, short-term statin therapy appeared to significantly improve chronic vascular inflammation and endothelial dysfunction with no adverse effects in children complicated by CAA late after KD. However, long-term and randomized studies are still needed to make further conclusions. (Circ J 2008; 72: 1583 - 1587)