BACKGROUND AND OBJECTIVES: Ten to twenty percent of children with Kawasaki disease (KD) do not respond to initial intravenous immunoglobulin (IVIG) treatment. If untreated, approximately 15% to 25% of KD patients have complications. The aim of this study was to find useful predictors of responsiveness to initial IVIG treatment in KD. SUBJECTS AND METHODS: We retrospectively reviewed medical records of 91 children diagnosed with KD at Myong Ji Hospital from March 2012 to April 2014. Before and after (24 hours to 36 hours) IVIG treatment, the following laboratory data were obtained: hemoglobin (Hb) level, white blood cell count, proportion of neutrophil, lymphocyte and eosinophil, platelet count, erythrocyte sedimentation rate (ERS), C-reactive protein (CRP), creatine kinase (CK), creatine kinase MB (CK-MB), and N-terminal pro-brain natriuretic peptide (NT-proBNP). Subjects were then divided into two groups: IVIG-responsive or IVIG-resistant. RESULTS: Of 91 patients, 11 (12%) required retreatment. By univariate analysis, before-IVIG laboratory parameters of white blood cell count, % neutrophil, ERS, CRP, sodium, CK, CK-MB, and NT-proBNP were significantly different between IVIG-responsive and IVIG-resistant patient groups. In the after-IVIG laboratory parameters, Hb level, white blood cell count, % neutrophil, % lymphocyte, CRP, CK, CK-MB, and NT-pro-BNP were significantly different between the two groups. While the mean-differences were not statistically significant, fractional change (FC)-CRP and FC-% neutrophil showed significant difference. By multivariate analysis, FC-CRP was confirmed to be an independent predictor for initial IVIG resistance. CONCLUSION: Fractional change-C-reactive protein might be a useful and important value for predicting initial IVIG resistance in KD patients.