Background: Kawasaki Disease (KD) relapse is a risk factor for Coronary Artery Lesion (CAL) development. However, the frequency and outcomes of patients with relapse remain unclear. Objective: To determine the frequency and outcomes of patients with KD relapse and to ascertain the usefulness of treatment with initial single intravenous immunoglobulin (IVIG) therapy (2g/kg) with delayed use of aspirin (DUA). Materials and Methods: The outcomes of 207 patients who underwent initial single IVIG therapy at 2 g/ kg/ dose with DUA for KD were analyzed retrospectively. The patient data were divided according to whether the patients had relapses (relapse group, n=5) or not (non-relapse group, n=202). KD presentations were considered as relapses when a second episode appeared within 2 months of the first one. Stat Flex version 6 for Windows was used for all statistical analyses. Chi-square, Fisher’s exact, and Mann-Whitney U tests were used as appropriate, with sample size considerations. Results: The frequency of patients with disease relapse was 2.4%. The five patients who experienced relapses (two boys and three girls; median age, 10 months; range, 3 months to 3 years 11 months) received initial IVIG therapy at 5 days of illness. The median day of illness for the relapse was 16 (range, 12-29). No patients with disease relapse developed CAL. The rate of incomplete type, IVIG resistance and CAL, and timing of initial IVIG therapy with regard to the days of illness were similar between the relapse group and the non-relapse group. Three parameters, including serum C-reactive protein, albumin values, and Neutrophil-to-Lymphocyte ratio (NLR) before and after initial IVIG, were similar between the two groups. Although not statistically significant (P=0.055), the median NLR after initial IVIG therapy of the relapse group was higher than that of the non-relapse group (2.48 vs. 0.84). Conclusion: An initial single IVIG therapy (2g/ kg/ dose) with DUA for KD may lead to a low KD relapse frequency and to favorable patient outcomes.