Infective endocarditis (IE) is a rare disease in pediatrics compared with that in adults. Conventionally, IE is triggered by an access of pathogens into the bloodstream coupled with altered endothelial integrity on the valve surface. Without timely diagnosis and treatment, IE can develop serious complications including thromboembolism, hemodynamic deterioration due to valvar dysfunction, refractory infections with multiple organ failure, and death. Pre-existing heart disease continues to be a major predisposing factor for the development of IE, but recent medical advances with more aggressive treatment strategies have substantially changed the epidemiology of IE in pediatrics. Hospital-acquired IE in vulnerable populations, including those with prematurity, immunodeficiency, cancer, hemodialysis, or indwelling central line, are at risk for inpatient mortality. Increased incidence of atypical IE without underlying heart disease has been reported in both children and adults. Although most of IE follows common pathogenesis, there are some differences in infants and children compared with that in adults. In this entry, we review the basic principle of pathogenesis and pathophysiology of IE, especially as to how local intracardiac infection spreads to progressive systemic disease and characterize the specific features of IE occurring in young individuals.