This study aimed to determine the effects of intravenous methylprednisolone pulse (IVMP) therapy on cytokine levels in patients with acute Kawasaki disease (KD) unresponsive to initial intravenous immunoglobulin (IVIG) therapy. Fifteen KD patients unresponsive to initial IVIG, 2 g/kg/day, were randomized to receive IVMP (n = 7), 30 mg/kg/day for 3 days or additional IVIG (n = 8), 2 g/kg/day, and plasma cytokine levels were compared. The fraction of febrile patients was significantly lower in the IVMP group than in the additional IVIG group on day 2 (0/7 vs. 3/8, p = 0.03), but not on day 4 and later (3/7 vs. 4/8, p = 1.00) because of recurrent fever. The prevalence of coronary lesions was similar between the two groups (2/7 vs. 2/8, p = 1.00). The ratios of plasma levels of tumor necrosis factor-alpha and monocyte chemoattractant protein-1 to those at enrollment (defined as day 1) were significantly lower in the IVMP group on day 4 (0.50 +/- 0.27 vs. 1.01 +/- 0.46, 0.53 +/- 0.39 vs. 0.93 +/- 0.44, p = 0.02 and 0.045, respectively), but not on day 7 (0.54 +/- 0.34 vs. 0.88 +/- 0.39, 0.76 +/- 0.39 vs. 0.61 +/- 0.17, p = 0.07 and 0.83, respectively). The ratios of interleukin-2 receptor, interleukin-6, and vascular endothelial cell growth factor to those at enrollment did not differ significantly between the two groups. In conclusion, for KD patients unresponsive to initial IVIG, IVMP suppresses cytokine levels faster, but subsequently similarly, compared with additional IVIG.