Graft failure has remained a limitation of umbilical cord blood transplantation (CBT). Here, we assessed the outcomes of patients who experienced graft failure after CBT. Inclusion criteria were patients (age ≥ 18 years) experiencing graft failure after unrelated CBT (single or double) between 2005 and 2016, for acute myelogenous leukemia (AML) or acute lymphoblastic leukemia (ALL), no prior allogeneic or autologous transplantation, no other stem cell product. The study included 87 patients. At 1-year, cumulative incidence of relapse and nonrelapse mortality (NRM) was 35% and 37%, respectively. One-year overall survival (OS) and progression-free survival (PFS) was 40% and 29%, respectively. Forty-six patients underwent a salvage second transplantation with 1-year and 2-year OS and PFS from second transplantation 41% and 34% for OS, and 37% and 34% for PFS, respectively. In multivariate analysis, complete remission (CR) at CBT (HR = 0.45, 95% CI 0.25–0.83, P = 0.01) and reduced-intensity conditioning (HR = 0.51, 95% CI 0.29–0.91, P = 0.023) were associated with better OS. In conclusion, in this retrospective study, we observed that approximately one-quarter of patients experiencing graft failure after CBT remained alive without relapse 2 years later.