Arrhythmias often complicate the management of heart failure and contribute to mortality and morbidity. Implantable cardioverter defibrillators are the best protection from death caused by ventricular arrhythmias, but their benefit will probably be less in heart failure populations than has been observed in trials that have not focused on heart failure populations. Implantable cardioverter defibrillators are first-line therapy for high-risk patients who have been resuscitated from sustained ventricular tachycardia or ventricular fibrillation, who have inducible ventricular tachycardia in the setting of previous myocardial infarction, or who have unexplained syncope. Amiodarone is the major pharmacologic option for treatment of symptomatic arrhythmias. In selecting therapy, the severity of heart failure and cause of heart failure are important considerations. Atrial fibrillation occurs with increasing frequency as the severity of heart failure increases. Anticoagulation and rate control are important. Attempted maintenance of sinus rhythm with amiodarone or dofetilide is a reasonable consideration for selected patients, although the benefit of treatment strategies that seek to maintain sinus rhythm has not been demonstrated. Ongoing trials will provide further guidance for arrhythmia management.