Kawasaki disease (KD) is a systemic vasculitis and occurs among Japanese children at a high incidence. Serum bilirubin and heme oxygenase-1 (HO-1) expression are known to play a significant role in the protection of vascular endothelial cells. Japanese have unique polymorphic distribution patterns of (TA)7 or G71R of the bilirubin UDP-glucuronosyltransferase (B-UGT) gene and of (GT)n repeats of the HO-1 gene. We investigated the relationship of KD susceptibility with these polymorphisms. There were no significant differences in the distribution of allele frequencies and genotypes of these polymorphisms between KD patients and controls. These polymorphisms are not associated with KD susceptibility.