A second allogeneic (allo) hematopoietic cell transplant (HCT) is an important therapeutic consideration for patients relapsing after their first. We conducted a retrospective review of 41 pediatric patients with leukemia that underwent a second allo-HCT at our institution. Overall, 53.7 and 43.9 % of patients were alive and disease-free at 1 and 5 years, respectively, after the second allo-HCT. The factors affecting outcome by both univariate and multivariate analysis were interval between transplants and the use of a myeloablative conditioning (MAC) regimen prior to second transplant. Outcomes were inferior in patients who received their second transplant <6 months from their first HCT when compared to patients in whom the interval between HCTs was 6-12 or more than 12 months. Interval between HCTs was also significant when each type of leukemia (acute lymphoblastic leukemia (ALL) n = 21, acute myelogenous leukemia (AML) n = 11, and chronic myelogenous leukemia (CML) n = 7) was analyzed separately. In univariate analysis, use of the same donor and use of a matched sibling donor resulted in significant improved outcome. There was not a significant association between disease-free survival (DFS) and age, remission status, use of total body irradiation (TBI) before second HCT, or type of leukemia. Second allogeneic HCT can be a curative therapeutic option for leukemia patients relapsing after their first transplant. As more targeted therapies have become available, patients that relapse after first HCT are more likely to achieve remission. Therefore, it is anticipated that there will be more candidates for second HCT with improved performance and remission status, ultimately leading to a better outcome with the second HCT.