Patients with congestive heart failure frequently have ventricular arrhythmias on ambulatory electrocardiographic recordings and sudden cardiac death is seen in almost 50% of such patients. Many antiarrhythmic agents have been approved to suppress the arrhythmia in an effort to improve survival. Some sodium-channel blockers not only failed to improve survival but have been shown to be harmful. This led to the development of potassium-channel blockers, such as d-sotalol, amiodarone, dofetilide, and azimilide. d-Sotalol was associated with excess mortality in patients with left ventricular dysfunction; amiodarone seems to be potentially beneficial; and dofetilide has a neutral effect on mortality. The Sudden Cardiac Death Heart Failure Trial (SCD HEFT) is testing the implantable cardioverter defibrillator (ICD) against amiodarone and placebo. The ICDs appear to be superior to antiarrhythmic drugs in certain high-risk patients, although not proved in unstratified patients with heart failure.