Adolescents often fare poorly after heart transplantation (HT) compared to other age groups. However, it is unknown if the impact of age varies across diseases leading to HT. We tested the hypothesis that age-related HT outcomes are different in patients with congenital heart disease (CHD) vs myocarditis.A retrospective analysis of the United Network of Organ Sharing database was performed for patients with myocarditis (n=709) and CHD (n=1,631) undergoing HT from 1987-2011, to assess the effect of age on graft survival. Age was categorized as children (6-12 years), adolescents (13-18 years), younger adults (19-30 years), and older adults (31-50 years).Adolescents comprised 28% of CHD patients and 14% of myocarditis patients (p<0.001). Compared to older patients, adolescents were more likely to be listed as Status 1A, were less likely to have diabetes, and spent fewer days on the transplant wait list (p<0.05 for all). For CHD, the median graft survival for adolescents was 7.4 years (95% CI 6.4-8.3), which was not significantly different from other ages [9.0 years (95% CI 7.4-10.6) for children (p=0.4), 11.2 years (95% CI 8.6-13.7 for younger adults (p=0.4), and 11.3 years (95% CI 8.0-14.6) for older adults (p=0.3)]. For myocarditis, the median graft survival for adolescents was 6.9 years (95% CI 4.8-8.9), which was significantly lower than other age groups [14.1 years (95% CI 9.8-18.4) for children (p=0.01), 11.8 years (95% CI 8.8-14.8) for younger adults (p=0.08), and 12.0 years (95% CI 10.3-13.7) for older adults (p=0.005)]. On multivariable analysis, adjusting for donor and recipient characteristics, adolescent age was independently associated with worse survival for patients with myocarditis (p=.01), but not for CHD.Adolescents with myocarditis have significantly worse graft survival after HT, but adolescents with CHD have similar outcomes to other patients with CHD. Further study is needed to improve outcomes in this vulnerable population.