Methods/design: This trial has been designed as a multi-center, prospective, randomized controlled, evaluator-blinded trial with two parallel groups to determine whether IVIG alone as the primary therapy in acute-stage KD is as effective as IVIG combined with high-dose aspirin therapy. The primary endpoint is defined as CAL formation at 6-8 weeks. Patients meeting the eligibility criteria are randomly assigned (1:1) to a test group (that receives only IVIG) or a standard group (that receives IVIG plus high-dose aspirin). This clinical trial is conducted at seven medical centers in Taiwan.