Abstract: AIM To investigate genetic variations in the FGF-23 gene in children with Kawasaki syndrome and its association with serum FGF-23 levels and eventual development of cardiac abnormalities. METHODS Ninety children with Kawasaki disease (from January 2013 to January 2015) in our hospital were selected for this study and FGF-23 gene intron polymorphism and incidence of heart disease were examined. According to different genotypes of FGF-23, 90 cases were divided into FGF-23 gene polymorphism group and FGF-23 gene wild-type group.Serum FGF-23 level, serum-related indicators and susceptibility of heart attack were compared between groups. RESULTS Of the 90 cases, 64 cases had the FGF-23 wild-type genotype (71%) and 26 had the FGF-23 gene polymorphism (29%). The proportion of males and serum FGF-23 levels in FGF-23 gene polymorphism group were significantly higher than those in FGF-23 wild-type gene group ［92%, (41±15) pg/ml vs. 62%, (11±13) pg/ml; P<0.05］. The incidence of coronary aneurysms or dilatation in the FGF-23 gene polymorphism group was significantly higher than in the wild-type FGF-23 gene group (P<0.05). CONCLUSION Serum FGF-23 levels of patients with Kawasaki disease and FGF-23 gene polymorphism are significantly increased and the risk of coronary artery abnormalities is increased.