PURPOSE: To determine the optimal time of high dose intravenous immune globulin (IVIG) treatment, we analysed the clinical characteristics and progress of a group of Kawasaki disease patients who had early treatment with IVIG. METHOD: A retrospective study was conducted of 188 patients with Kawasaki disease who were admitted to Yeungnam University Medical Center from January 2000 to December 2005. All patients were treated with a high dose IVIG and high dose aspirin for the initial acute phase treatment. The early treatment group consisted of 94 patients who received treatment before 5 days of fever, and the conventional group consisted of 94 patients who were treated on or after day 5. The patients' sex, age, laboratory findings, total duration of fever, duration of fever after initial IVIG, need for additional IVIG and coronary artery status were noted. RESULT: There were no significant differences between the two groups in sex ratio and age. No significant differences were noted in the level of WBC count, ESR, CRP, serum albumin, LDH, total duration of fever and coronary abnormality. But the value of ALT(151.8+/-17.3 vs. 81.9+/-13.4, P=0.002), duration of fever after initial IVIG (3.8+/-0.5 days vs. 2.1+/-0.2 days, P=0.003), and rate of additional IVIG (15.9% vs. 6.3%, P=0.037) were significantly higher in the early treatment group. There was no significant difference in initial dose of IVIG, but dosage of aspirin was lower in early treatment group (P=0.037). CONCLUSION: There is no evidence that early treatment of IVIG has greater efficacy in preventing cardiac sequelae than conventional treatment. In addition, early treatment is likely to result in a greater requirement for additional IVIG treatment.