The effect of serum of patients with Kawasaki disease (KD) on expression of platelet-derived growth factor (PDGF) B chain protein in vascular endothelial cells (VEC) was studied by immunocytochemical method. Meanwhile, the effects of the endothelial cell conditioned media (ECM) on expression of PDGF receptor mRNA in vascular smooth muscle cells (VSMC) and on cell cycle of VSMC were investigated by the methods of nucleic acid hybridization and flow cytometry (FCM). The results showed that the serum of patients with KD induced the expression of PDGF-B chain protein significantly. ECM significantly promoted the expression of PDGF receptor mRNA and induced the proliferation of VSMC. These data suggest that the activation of PDGF-PDGF receptor may play a role in the pathogenesis of coronary complication of KD.