Cardiopulmonary bypass (CPB) induces systemic inflammatory response syndrome (SIRS), which may contribute to postoperative morbidity. Neonates experience an exaggerated inflammatory response and may be at a higher risk for the deleterious effects of CPB. SIRS may disrupt the hypothalamic-pituitary-adrenal (HPA) axis leading to a relative adrenal insufficiency (AI) after neonatal CPB. There is some emerging evidence supporting an association of AI with morbidity in neonates after cardiac surgery. Postoperative steroids may offer hemodynamic benefits to neonates suffering from low cardiac output syndrome (LCOS) following CPB. Benefit of postoperative steroids is multifactorial including: suppression of inflammatory cytokines, direct actions on the heart and vascular smooth muscle, and treatment of AI in a subset of patients.