A preliminary study was carried out from 2000 through 2005, mostly in Gunma University's affiliated hospitals, to investigate the usefulness of initial combined therapy with immunoglobulin and prednisolone (a multicenter, randomized, open-label, controlled study). The results showed that initial co-administration of immunoglobulin and prednisolone (1) significantly decreased the frequency of coronary artery dilation during the course of the disease, (2) tended to reduce the incidence of coronary sequelae, (3) decreased the total dose of immunoglobulin administered by reducing the incidence of nonresponsiveness to initial treatment, and (5) quickly lowered fever and improved inflammatory response. If similar effects are obtained in the present clinical study, the following effects can be anticipated:

	1. A new method for treating Kawasaki disease patients will be established. 2. The number of Kawasaki disease patients who develop coronary sequelae will decrease. 3. Reducing the number of patients resistant to treatment will decrease both the amount of immunoglobulin required and the cost of treating acute Kawasaki disease cases. 4. A decrease in the number of Kawasaki disease patients who develop coronary sequelae will reduce medical costs that accrue during the follow-up and post-discharge periods.