BACKGROUND : Myocarditis, myocardial ischemia and infarction are the most serious complications of coronary artery lesions in children with Kawasaki disease (KD). Especially under 1 year-old infant patients, may have the severe progress of the disease than older children, regardless of uncommon incidence. Therefore, early detection and treatment of myocardial abnormality is crucial. Tissue Doppler imaging with strain measures seem to be a promising means to predict myocardial functional changes during the time period of Kawasaki disease in this infant patients. METHODS : Twenty patients in Kawasaki disease who had coronary arteriopathy were enrolled and evaluated using Tissue Doppler imaging. Pulsed tissue Doppler velocity data, strain, time to peak strain were measured both in acute phase and convalescent phase(treated for 3 months after diagnosis). Then the data of two phases were compared in these infant Kawasaki patients. RESULTS : The measures of S��� wave velocity and strain were significantly different between acute phase and convalescent phase in these infant Kawasaki disease patients. Systolic peak velocity of pulsed wave tissue Doppler measure and strain demonstrated decreased value in convalescent phase, and time to peak strain was delayed. CONCLUSION : TDI can be used with strain measures for assessment of myocardial function in infant patients with Kawasaki disease. In convalescent phase, myocardium may not seem to better work yet, need to be treated more for myocardial functional recovery. This may inform to assess myocardial dysfunction from coronary arteriopathy in infant Kawasaki disease patients, both in acute phase and the treatment period for appropriate lasting myocardial recovery.