Although the death rate from cardiovascular disease has decreased, nearly 2400 Americans die from cardiovascular disease each day (an average of one person every 37 seconds). Sudden cardiac death (SCD) affects individuals in the prime of their lives, with resuscitation rates successful in only a minority of patients, in part due to absent defibrillation by lay responders. After the publication of positive trials, the Centers for Medicare & Medicaid Services approved the implantable cardioverter-defibrillator (ICD) for the primary prevention of SCD. More recently, ICD therapy also has been shown to be effective for the primary prevention of SCD in patients with systolic heart failure, sometimes with the addition of cardiac resynchronization therapy. This article reviews the current status of primary prevention ICD therapy.