AB Graft failure and aplasia are known complications of umbilical cord blood (UCB) hematopoietic stem cell transplantation (HSCT). In the absence of a second HSCT, graft failure is generally a fatal complication due to overwhelming infection. We describe 2 children with primary graft failure and life-threatening infections after UCB HSCT who were rescued by the use of related haplocompatible T-cell-depleted peripheral blood stem cell transplants. The rapid availability of haplocompatible donors and the brisk neutrophil recovery after haplocompatible peripheral blood stem cell transplant with high numbers of CD34+ cells make this an attractive rescue strategy for patients with graft failure after UCB HSCT.