To examine the relationship between age and outcome after implantable left ventricular assist system support, the authors investigated the results of 223 patients from 17 centers who were supported with a HeartMate (Thermo Cardiosystems, Inc., Woburn, MA) pneumatic left ventricular assist system between 1986 and 1994. In addition, the authors examined a single center's experience with 67 patients between 1992 and 1996. Ages are separated by decile and ranged from 10 to 69 years. Men dominated all age groups, averaging 82% of the total (range, 64-91%). Viral, idiopathic, and post partum cardiomyopathies were the indication for support in 88% of the patients younger than 39 years of age. Ischemic cardiomyopathy was the cause of myocardial failure in the majority of patients older than 40 years of age (40-49 years, 54%; 50-59 years, 57%; and 60-69 years, 67%). Patients aged 40-59 accounted for 64% of the patients supported, and had the best outcomes both on support and after transplantation. Survival to transplantation was not significantly different among the groups, although the patients older than 60 and younger than 69 years of age had higher mortalities on support, most commonly from cardiac failure. At the Cleveland Clinic Foundation, the survival to transplantation and survival to discharge were indistinguishable between age groups. Age does not appear to be significant risk factor for outcome after implantable left ventricular assist system support. These results predict acceptable mortality for patients supported who are older than the age of 60.