Kawasaki disease is an acute vasculitis of possible infectious cause, which in particular affects the coronary arteries. Young children rely mostly on their innate immune system for protection against invading microorganisms, of which mannose-binding lectin is an important component. We aimed to investigate the possible role of the gene for this molecule (MBL) in white Dutch patients with Kawasaki disease. In 90 patients, frequency of mutations in the MBL gene was higher than in healthy children. In children younger than 1 year, those with mutations were at higher risk of development of coronary artery lesions than were those without (odds ratio 15.7, 95% CI 1.4-176.5, p=0.026). Our findings suggest that the innate immune system contributes differently to pathophysiology of Kawasaki disease at various ages.