Although graft failure (GF) is a fatal and life-threatening complication of umbilical cord blood transplantation (CBT), the standard treatment has not been established. We describe the case of a 28-year-old man diagnosed with acute myelogenous leukemia with myelodysplasia-related changes harboring a normal karyotype. This patient underwent 2 courses of idarubicin and cytosine arabinose therapy, and 3 courses of high-dose cytosine arabinose therapy. Subsequently, he underwent high-dose chemotherapy (total body irradiation and cyclophosphamide) followed by first CBT. Primary GF occurred after post-immunological reaction and hemophagocytic lymphohistiocytosis, and was diagnosed on day 27 after the first CBT. Therefore, the patient underwent secondary CBT for GF treated with a modified one-day conditioning regimen consisting of fludarabine (30 mg/m², 3 days), cyclophosphamide (2 g/m²), and total body irradiation (2 Gy), and graft-versus-host disease prophylaxis consisting of mycophenolate and tacrolimus. Consequently, the patient achieved neutrophil engraftment on day 17 after the second CBT. During the clinical course of the second CBT, the main complications were sepsis, BK virus-associated cystitis, and acute graft-versus-host disease (skin, grade 2, stage 3). After these treatments, the patient was disease-free for 39 months. Our case suggests that these treatments may be feasible, safe, and effective for the treatment of patients with GF. This case study may be helpful to physicians who directly care for GF patients, and may provide a future direction for a more efficient treatment modality. [J Clin Exp Hematop 55(2) : 89-96, 2015]