We assessed whether duration of nonischemic cardiomyopathy was related to the degree of benefit from implantable cardioverter-defibrillator (ICD) insertion. Subjects who had a recent diagnosis of nonischemic cardiomyopathy had at least a similar benefit from ICD insertion as did those with a remote diagnosis. These results indicate that ICD therapy should be considered in such patients as soon as they are diagnosed and once reversible causes of left ventricular dysfunction have been excluded.