Kawasaki disease (KD) is associated with pancarditis and complicated by coronary artery (CA) inflammation. In the present case, we were confronted with a very ill KD patient with first degree atrioventricular block and QS pattern on the electrocardiogram. This unusual pattern was transient and intermittent. It reflected a conduction disturbance in the context of an acute myocarditis rather than an immediate CA complication. We herein discuss the differential diagnoses of a rarely observed electrocardiographic finding in the young.