Of 75 patients meeting clinical criteria for Kawasaki disease, 67 patients were followed with serial ECG and echocardiograms (echo) for at least 1 year. Sixteen patients had coronary artery aneurysms and three had dilated coronary arteries as assessed by initial two-dimensional (2D) echo and/or angiocardiographic studies. ECG findings of first and second-degree heart block and ST-T wave changes (36%) as well as M-mode echo abnormalities (45%) including pericardial effusion, decreased ventricular septal motion, and decreased left ventricular function were all normalized by 6 months, except in two infants who continued to have decreased function and flat ventricular septal motion. In four patients with single proximal coronary aneurysm and two with dilated coronary artery, resolution of lesions occurred by 1 year. Among 11 patients with multiple coronary aneurysms discovered by initial studies, the 2D echo became normal in seven and showed aneurysms in four as corroborated by angiogram. One patient with an isolated distal coronary aneurysm, not seen by initial or serial echo, had a normal follow-up angiogram. Our study suggests that in Kawasaki disease careful, serial, 2D echo is sufficient to monitor the course of coronary artery disease that tends to regress and follow a benign course. However, the long-term effects of this disease on cardiac and coronary arteries remain to be elucidated.