Myocardial dysfunction is the leading cause of death in single-ventricle patients. Heart transplantation has traditionally been reserved for Fontan patients with end-stage myocardial dysfunction. Cardiac resynchronization therapy with multisite pacing was found to improve the myocardial performance in Fontan patients in acute postoperative settings; however, its role is unclear in chronic Fontan patients with progressive myocardial dysfunction. We present a case in which cardiac resynchronization therapy improved both hemodynamics and clinical condition in a Fontan patient with advanced myocardial dysfunction.