Inflammatory disorders which may affect the heart muscle, the endocardium, the pericardium and/or the coronary arteries are rare, but potentially devastating diseases. As the incidence of rheumatic heart disease has decreased, children with congenital heart disease now constitute the primary patient population at risk of infective endocarditis. Streptococcus viridans and Staphylococcus aureus are still the most frequently observed organisms. The majority of children with infective endocarditis can be cured today, but good results depend on early diagnosis and accurate treatment. Myocarditis occurs when the heart muscle is involved in an inflammatory process. Causes are numerous, but most common in children are infections with cocksackie viruses. Approximately two-thirds of children with symptomatic acute myocarditis show complete recovery of impaired ventricular function, 10-20% progress of dilatative cardiomyopathy and about 10% die or require heart transplantation. Kawasaki disease is the most prevalent inflammatory coronary artery disease and the leading cause of acquired heart disease in children. The origin of this acute systemic vasculitis remains unknown. Visible coronary arterial abnormalities develop in approximately 20% of children with untreated Kawasaki syndrome. A single dose of gamma-globulin (2 g/kg over 12 h) given within the first 10 days of onset of illness as early as possible, in addition to aspirin has been shown to reduce the duration of fever, which may reflect the severity of ongoing vasculitis, and to reduce the prevalence of coronary artery anomalies.