As many as 21 children suffering from infectious endocarditis (IE) were examined for the clinical and morphological picture of the disease. The patients' age ranged from 2 to 15 years. In 15 children, IE developed in association with different congenital diseases; in one patient, in the presence of rheumatic heart disease, and in 5 patients, in unaffected heart valves. The sectional material was examined in 19 cases whereas the operational material in 2 cases. Analysis of the data obtained has shown that early diagnosis of IE (primary and secondary) may not infrequently be fairly difficult, which is likely to result in the late administration of antibacterial therapy. In addition to the involvement of the valvular apparatus of the heart, the majority of the patients demonstrated the signs of focal myocarditis and postmyocarditic cardiosclerosis, which is one of the causes of the development of refractory heart insufficiency. IE children mostly die from heart insufficiency and thromboembolism.