The authors compared pre-treatment and posttreatment characteristics of 206 prospectively enrolled patients with Kawasaki disease (KD) responsive to intravenous immunoglobulin (IVIG) with those of 23 (10% of total) IVIG non-responders. Demographic characteristics were similar in both groups. Compared to IVIG responders, non-responders had a longer total duration of fever and a higher incidence of coronary artery lesions. Prior to IVIG, non-responders had higher neutrophil differential and C-reactive protein, and lower cholesterol. 24 hours after the IVIG infusion, a total leucocyte count >13.1×10 9/l, neutrophil differential >51% and total protein <72 g/l showed reasonable sensitivity (91%, 91% and 64%, respectively) and specificity (89%, 76% and 78%, respectively) as independent characteristics of non-response to IVIG. Laboratory parameters before and shortly after IVIG may reflect the severity of inflammation in KD patients and assist in informing further management.