BACKGROUND AND OBJECTIVES: Reports on the incidence of intracardiac thrombi (ICT) have increased over the last few decades, but ICT are still relatively rare among children. Left ventricular systolic dysfunction and dilatation may contribute to the formation of ICT, especially when a hypercoagulable state exists. The aim of this study was to describe the incidence of ICT in children suffering from cardiac failure with left ventricular dysfunction and to identify risk factors on admission for developing ICT. SUBJECTS AND METHODS: We conducted a retrospective chart review of children up to 18 years of age admitted to the Pediatric Intensive Care Unit due to cardiac failure with left ventricular dysfunction between January 1, 2003 and December 31, 2008. RESULTS: Twenty-one patients were admitted with clinical signs of cardiac failure and echocardiographic findings compatible with dilated cardiomyopathy or acute myocarditis. Dilated cardiomyopathy was diagnosed in 11 patients (52%). Adenoviruses and enteroviruses were suspected to be the cause of acute myocarditis in 5 cases. The personal or family history of hypercoagulable states were obtained from 19 out of 21 patients (90%). Among patients with a hypercoagulable state, 3 out of 7 developed ICT compared with none out of 12 among patients without hypercoagulability (p=0.043). Two of these 3 patients experienced an embolic event. CONCLUSION: Cardiac failure with left ventricular dysfunction may predispose the patient to ICT and increase the risk of thromboembolism, especially when an underlying hypercoagulable state exists. The hypercoagulable state must be carefully evaluated on admission in these patients.