Purpose: A part of patients with Kawasaki disease(KD) may persist a fever after IVIG therapy(10~20%) and have a coronary artery lesion(CAL). The responsiveness of IVIG according to a patient may relate to an anti-inflammatory mechanism, a interaction with Fc gamma receptors and a half-life of IVIG. There have been few studies on the clinical comparison study for the responsiveness of IVIG therapy according to the level of IgG in Kawasaki patients. We studied that a change of IgG level as a usful predicting factor for failure to therapy or nonresponder in KD. Methods: 133 patients with acute KD on admission to Chungnam National University Hospital between 2005 and 2012 were enrolled in this study. We only include patients with complete KD. The levels of serum immunoglobulin were measured before, at 1 day after IVIG therapy. Results: 133 patients of them who were measured hemoglobin(Hb), white blood cell count(WBC), erythrocyte sedimentation rate(ESR) or C-reactive protein(CRP), level of IgG, IgA, IgM according to IVIG therapy and composed of 110 responder group and 23 non-responder group. 25 patients have coronary artery lesion.(10 patinet were nonresponder group, 15 patients were responder group) There was no significant differences in Hb, WBC, ESR or CRP. The levels of IgG in serum were no deference between responder group and non-responder group.(835.68 vs 746.96 mg/dL, p=0.15) And also there were no deference between no CAL and non-CLA group.(840.82 vs731.88 mg/dL, p=0.07) But the change of IgG level was significantly lower in responder (2303.61 vs 1962.45 mg/dL, p=0.02) and CAL group.(2309.37 vs 1894.44 mg/dL, p=0.006) Conclusion: Serum Ig G level, known risk factor in KD cann`t be predictor of nonresponseness or CAL. But, the change of Ig G after IVIG therapy can be predictor of nonresponseness or CAL.