Left ventricular noncompaction (LVNC) is a form of cardiomyopathy resulting from a disorder of endomyocardial morphogenesis. It has been associated with significant morbidity and mortality. The aim of this study was to characterize associated cardiac findings in children with LVNC and to identify risk factors associated with increased mortality. From our echocardiography database, we identified 46 patients diagnosed with LVNC between December 1999 and February 2005. The mean age at presentation was 3.6 ± 5.6 years, and the mean duration of follow-up was 1.9 ± 2.1 years. Left ventricular ejection fraction was decreased in 24 patients (52%; mean 39.5% ± 13.1%). Thirty-six patients (78%) had associated cardiac lesions, including atrial septal defect (n = 16 [35%]), ventricular septal defect (n = 17 [37%]), patent ductus arteriosus (n = 14 [30%]), and Ebstein’s anomaly (n = 5 [11%]). Electrocardiogram abnormalities were found in 80% of patients; most commonly they included left (n = 15 [43%]) and right ventricular hypertrophy (n = 19 [54%]). Documented arrhythmias included ectopic atrial rhythm (n = 2), junctional rhythm (n = 2), supraventricular tachycardia (n = 2), and ventricular tachycardia (n = 1). Overall mortality was 20%, and there was no association with ejection fraction, morphologic defect, or arrhythmia. Mean age at diagnosis in survivors (4.5 ± 6.1 years) was higher than nonsurvivors (0.4 ± 0.7 years) (p < 0.0001). LVNC is a rarely isolated form of cardiomyopathy, and it is associated with significant additional cardiac abnormalities. Although it does not have an invariably fatal course, early presentation in infancy does carry an increased risk of mortality.