Objectives: A critical shortage of donor organs has caused many centers to use less restrictive donor criteria, including the use of adult-age donors for pediatric recipients. The purpose of this study is (1) to describe the supply of pediatric (0-18 years) heart donors, (2) to explore the relationship between donor age and long-term survival, and (3) to define threshold age ranges associated with decreased long-term survival. Methods: The United Network of Organ Sharing provided deidentified patient-level data. Primary analysis focused on 1887 heart transplant recipients aged 9 to 18 years undergoing transplantation from October 1, 1987, to September 25, 2005. Kaplan-Meier analysis and log-rank tests were used in time-to-event analysis. Receiver operating characteristic curves and stratum-specific likelihood ratios were generated to compare survival at various donor age thresholds. Results: The number of pediatric donors decreased (P < .001) over the study period, particularly from 1993 (n = 640) through 2004 (n = 432). Among recipients aged 9 to 18 years, univariate analysis demonstrated a statistically significant (P < .001) inverse relationship between donor age and survival. Stratum-specific likelihood ratio analysis generated 3 strata for donor age: the low-risk, intermediate-risk, and high-risk groups consisted of donors aged 13 years or younger (n = 611, 32.41%), 14 to 51 years (n = 1258, 66.7%), and 52 years and older (n = 16, 0.85%), respectively. In the low-risk, intermediate-risk, and high-risk groups median survival was 4069 days (11.1 years), 3495 days (9.57 years), and 1197 days (3.28 years), respectively. Conclusions: Although donors aged 13 years or less offer pediatric recipients the best chance for achieving long-term survival, donors aged 14 to 51 years offer good outcomes to pediatric recipients. Consideration should be given to expanded use of well-selected adult-age donors for pediatric recipients. © 2006 The American Association for Thoracic Surgery.