Background: Allosensitization among children being considered for heart transplantation remains a great challenge. Controversy exists as to the best approach for those with elevated panel-reactive antibody (PRA) titers. We sought to define the association between elevated PRA and outcomes using data from the multi-institutional Pediatric Heart Transplant Study Group. Methods: Between January 1993 and December 2008, 3,016 patients (>1 month of age) were listed for heart transplantation. PRA data at listing were available for 2,500 (83%) patients, and 2,237 underwent transplantation with PRA data being available for 1,904 (85%). Because various PRA assays were employed (e.g., cell-based and solid phase) we entered the highest value regardless of methodology. Results: Among the factors associated with high PRA at transplant were Status 1 at listing, previous sternotomy and prior Norwood procedure. An elevated PRA at listing was associated with higher risk of death while waiting. Of subjects with PRA <50% only 57% were transplanted by 1 year on the waitlist, as compared with 76% of those with PRA <10%. Waitlist mortality for the highly allosensitized subjects (