Implantable cardioverter-defibrillators (ICD) have advanced from a hypothetical device (1970s), to the first human trials (1980s), to the current and future models capable of differentiating ventricular tachyarrhythmias and bradyarrhythmias and of applying selective electrical therapy. The device is successful in decreasing the expected high risk of sudden cardiac death in implantees from approximately 30% to approximately 2% at 1 year. However, because of the major surgical procedure required for implantation and cost of therapy, controversy remains regarding the specific selection of patients to whom the device should be offered. Technologic advances have expanded the potential applicability of this therapy but may simultaneously diminish the survival benefit because of the complexity and sophistication of programming. In this review, we discuss the current status of ICD use, controversies that have yet to be settled, and the direction of future devices based on recently available information.