Transesophageal echocardiography is more sensitive than transthoracic echocardiography (TTE) in detecting endocarditis in adults; however, pediatric data are limited. Retrospectively, 39 subjects with endocarditis were divided into adult-sized (≥60 kg) and pediatric-sized (<60 kg). TTE was 97% sensitive in pediatric-sized subjects but 70% in adult-sized subjects (P < 0.05). TTE is usually sufficient for detection of endocarditis in children <60 kg.