Background:Kawasaki disease (KD) is an acute systemic vasculitis syndrome with a high incidence of coronary aneurysms in untreated children. The majority of aneurysms resulting from KD are known to regress with time.Aims:This study aimed to determine the course and outcome of coronary artery dilatation in patients with KD and ascertain whether there are any differences in the outcomes in the different branches.Setting and Design:This is a retrospective cohort study of patients diagnosed with KD with midterm follow-up data.Methods:Serial echocardiography was performed in all KD patients with coronary dilatation for 1–10½ years. The Kaplan–Meier curve was used for statistical analysis.Results:There were 154 patients with coronary dilatation studied. The frequency of coronary dilatation in acute phase was 33.3% and decreased to 7.9% 6–8 weeks later. Each patient could have dilatations at more than one branch, so the total number of dilatations was 245. The median time needed for regression was 2.6 months (mean: 10.5 months) while the median of follow-up duration was 41 months (mean: 23 months). Small- and medium-sized dilatations had more favorable outcomes compared to the giant ones. Location of dilatation did not influence the outcome.Conclusions:The majority (77.4%) of small- and medium-sized dilatations regress within 2 years, but giant aneurysms tend to persist. The outcome of coronary dilatation is determined by the diameter and not by the location. Regression rate is faster in smaller dilatations. Left main coronary artery is the most frequent location for dilatation.