Periostin was upregulated 11-fold in acute and chronic Kawasaki disease coronary arteries compared with controls (P = 0.003). Kawasaki disease patients had significantly elevated serum periostin values compared with febrile controls (P = 0.0086). There was no relationship between serum periostin values and age, gender or acute phase reactants; there was a relationship between serum periostin and maximal coronary artery Z scores that did not reach significance (P = 0.08). Periostin may prove to be useful as a component of a future diagnostic biomarker panel for Kawasaki Disease.