Purpose. The prevalence of infective endocarditis (IE) among children with Staphylococcus aureus bacteremia (SAB) is unknown. The objective of this study was to determine prospectively the prevalence of IE among pediatric patients with SAB in a large tertiary care center. Methods. Between July 1998 and June 2001, all children who developed SAB whose parent/guardian signed informed consent underwent echocardiography. Clinical and follow-up results were collected prospectively. Endocarditis was classified according to the modified Duke criteria. Results. Fifty-one children developed SAB during the study interval. Definite (6 patients [11.8%] ) or possible (4 patients [7.8%]) IE was present in 10 of 51 (20%) children with SAB. Most children (73%) developed bacteremia as a consequence of an infected intravascular device. Children with underlying congenital heart disease had a significantly higher prevalence of definite or possible IE, compared with those with structurally normal hearts (53%vs 3%). All patients with definite IE had multiple positive blood cultures. Mortality was high among patients with and without IE (40%vs 12%). Conclusions. In this study, the preva- lence of definite IE among children with SAB was ～12%and was frequently associated with congenital heart disease and multiple positive blood cultures. The mortality for children with SAB and defi-nite or possible S aureus IE is high. Purpose. This objective was this prospectively the prevalence of IE among pediatric patients with SAB in a large tertiary care center. Methods. Between July 1998 and June 2001, all children who developed SAB whose parent / guardian signed informed consent underwent echocardiography. Clinical and follow-up results were collected prospectively. Endocarditis was classified according to the modified Duke criteria. Results. Fifty-one children developed SAB during Most children (73%) developed bacteremia as a consequence of (1%) of children with SAB. an infected intravascular device. Children with underlying congenital heart disease had a significantly higher prevalence of definite or possible IE, compared with those with structurally normal hearts (53 % vs 3%). All patients with definite IE had multiple positive blood cultures. Mortality was high among patients with and without IE (40% vs 12%). Conclusions. In this study, the prevalence of definite IE among children with SAB was ~ 12% and was frequently associated with congenital heart disease and multiple positive blood cultures. The mortality for children with SAB and defi-nite or possible S aureus IE is high.