Abstract: Objective：To analyze the relationship of VKORC1 gene polymorphism and warfarin maintenance dosage in Kawasaki disease children with coronary artery aneurysms aged from 6 months to 7 years. Methods：Clinical data of children under stable warfarin treatment for Kawasaki disease patients with coronary artery aneurysms and undergone genetic testing for VKORC1 were analyzed retrospectively. Associations of VKORC1 polymorphisms and clinical variables on warfarin maintenance dosage were assessed and a warfarin stable dosing algorithm was derived based on genetic and non-genetic factors. Results：Data of a total of 42 cases（0.5-6.7 years old）were collected. Thirty-five patients were male and 7 patients were female. The Warfarin maintenance dosage was 1.47±0.45 mg·d-1,and the weight-normalized Warfarin maintenance dosage was 0.11±0.033 mg·kg-1·d-1. The group comparing VKORC1 TT genotypes (0.10±0.021 mg·kg-1·d-1) required significantly lower daily doses than CT group (0.16±0.043 mg·kg-1·d-1）,P＜0.01. Compared with the children who underwent gene detection after warfarin, warfarin stability time was obviously shorten and the incidence of bleeding has a decreasing trend in children who underwent gene detection before warfarin. Two linear regression models were builed by setting different dependent variables: 1. Warfarin dose (mg·kg-1·d-1) =0.039+ 0.061×VKORC1 rs9923231(1 if TT,2 if CT), VKORC1 rs9923231 had significant influence on interindividual variation in warfarin stable dose, which contributed 43.8%. 2. Warfarin dose in (mg·d-1) =-0.407+0.088×weight+0.580×VKORC1 rs9923231(1if TT, 2 if CT）, In the full regression model, the combination of VKORC1 and weight explained 63.2% of dosing variability,VKORC1 and weight contributed 19.5％,43.7% respectively. The second warfarin stable dosing algorithm was superior to the first algorithm for higher R2. ConclusionIn：Kawasaki disease population with coronary artery aneurysms aged from 6 months to 7 years, VKORC1 is the main genetic factor relative to warfarin maintenance dosage. Weight is the main influence factor to warfarin maintenance dosage. The warfarin stable dosing algorithm may be useful for helping clinicians to prescribe warfarin with greater safety and efficiency.