PURPOSE--To assess infective endocarditis (IE) predisposing factors, etiologic agents and hospital course in infants and adolescents. METHODS--We Studied 222 patients admitted under compatible IE diagnosis, from 1985 to 1990. The population of this study is fifty patients (23//) under 16 years of age. RESULTS--Rheumatic valvular disease, as predisposing cardiopathy was proeminent within 9 to 16 years of age, markedly Statistical difference when compared to age range of 0 to 8 years (p < 0.05). Among congenital cardiopathies, the most frequent were: interventricular septal defect (26.0//) and tetralogy of Fallot (21.7//). Blood cultures, surgical material or emboli cultures were positive in 35 (70.0//) assessed patients. Streptococcus viridans (45.7//) and Staphylococcus aureus (42.8//) were the etiologic agents most often isolated. It was found that endocarditis by Staphylococcus aureus had mortality rate of 53.3//[(clinical (66.6//) and surgical (44.4//)], (p < 0.05) when compared to those by Streptococcus viridans; with total mortality of 6.2//(no clinical death and 16.6//in the surgical group). Total in-hospital mortality (clinical and surgical) was 26.0//(13 deaths). CONCLUSION--IE in infants and adolescents in this studied population presented Streptococcus viridans responsible for 46.7//of patients with endocarditis and the Staphylococcus aureus for 42.8//were the etiologic agents most often found. Total, clinical and surgical mortality was greater in patients with endocarditis by Staphylococcus aureus when compared with those by Streptococcus viridans. Among the congenital cardiopathies, whether operated on or not, ventricular septal defect and of Fallot's tetralogy were the most involved ones; rheumatic cardiopathy Still remains a significant predisposing factor to infective IE in our country