Despite the obvious psychosocial stress associated with pediatric heart transplantation, there has been little research conducted on the psychological impact of this highly invasive treatment. In this article we report on the personality functioning of 15 adolescent heart transplant recipients who completed the Millon Adolescent Personality Inventory. Psychological distress was common in the sample, and behavioral tendencies were more consistent with internalizing types of behavior. Different personality patterns emerged when patients who had received their transplant because of congenital disease were compared with those who had acquired cardiac conditions. Patients with a history of congenital disease endorsed more passive and dependent characteristics, which is consistent with both previous research and clinical practice. The findings are discussed within a developmental model of maladjustment.