We evaluated the effects of high-dose intravenous immunoglobulin (IVIG) administration on various protein parameters, including inflammatory profiles, in children with Kawasaki disease (KD). Sixty-three children with KD were treated with IVIG at 2 g/kg over 12 h. Serial examinations of laboratory indices were performed three times: before IVIG treatment, 24 h after IVIG treatment, and 7 days after IVIG treatment. The white blood cell and neutrophil counts showed significant decreases 24 h and 7 days after IVIG administration. The erythrocyte sedimentation rate (ESR) increased significantly 24 h after IVIG, and the elevated level was sustained for 7 days. The levels of hemoglobin, albumin and inflammation-associated proteins, including C-reactive protein, decreased 24 h after IVIG treatment. Inflammation-associated proteins, except transferrin, decreased further to near normal levels after 7 days. On the other hand, IgM and IgA were not affected after 24 h, rather increased significantly after 7 days. High-dose IVIG causes immediate changes in the levels of various proteins, except IgA and IgM, and downregulates the activated levels of inflammatory indices, except ESR, in the acute stage of KD.