Biomarkers have established an important role in the diagnosis and prognosis of heart failure in adults. Several biomarkers of different classes have also demonstrated a practical or potential role in managing patients with heart failure. In the pediatric population, objective assessment of severity and disease progression is apt to be more difficult. Therefore, biomarkers may represent an objective tool to confirm functional status and echocardiographic indices of left ventricular dysfunction in children with heart failure. Since early detection of remodeling is vital to preemptive management, biomarkers may also serve to gauge the severity of the ventricular remodeling process in several different diseases. Thus far, B-type natriuretic peptide levels have been found to be associated with the severity and outcome of heart failure in children, correlating with symptom severity, functional status and degree of left ventricular remodeling. They have been found to predict cardiovascular events, and may guide medical treatment decisions in symptomatic heart failure. High-sensitivity C reactive protein, cytokines, cytokine receptors, cardiac troponins and gene expression profiling are all emerging as a useful assessment tools in adults with heart failure. Further study is required to validate the role of these measures in children with cardiomyopathies and with heart failure.