OBJECTIVES:To describe the epidemiology, response to therapy, and outcomes of Kawasaki disease in a multiethnic community with a large Hispanic and Asian population. STUDY DESIGN:We analyzed prospectively collected data from 788 unselected patients with Kawasaki disease diagnosed and treated at a single medical center over a 10-year period. RESULTS:The average incidence of Kawasaki disease in children <5 years in San Diego County over the 10 years from 2006 to 2015 was 25 per 100 000 children, with the greatest incidence (50 per 100 000) for Asian/Pacific Islanders. Compared with other race/ethnicities, Asian/Pacific Islander patients with Kawasaki disease were younger, were diagnosed earlier in the course of their fever, had higher levels of inflammatory markers, and were more likely to develop aneurysms. There was no difference across race/ethnicity groups in response to intravenous immunoglobulin therapy. Filipino children had the highest recurrence rates (9.1%; 95% CI, 3.0%-22.6%) and 12 of 788 patients (1.5%) had a first- or second-degree relative with a history of Kawasaki disease. After correcting for age of onset, sex, and illness day at diagnosis, Asian/Pacific Islander children had an increased risk of developing aneurysms (aOR, 2.37; 95% CI, 1.37-4.11; P = .002). Overall, 180 of 788 patients (22.8%) had a maximal Z score of 2.5-10.0 and 14 of the 788 patients (1.8%) had a maximal Z score ≥10.0 despite 84% of these patients being treated within 10 days of fever onset. CONCLUSIONS:Our data provide new insights into the natural history of treated Kawasaki disease in a multiethnic population. Patient race/ethnicity influenced susceptibility to Kawasaki disease, timing of diagnosis, coronary artery outcome, and recurrence rates.