Purpose: Therapy-related myeloid neoplasms (t-MNs) are very rare in children. This study was aimed to characterize t-MNs developed from childhood cancers and to analyze their outcome. Methods: We reviewed the medical records of 16 patients who were diagnosed as t-MNs from 2002 to 2012 at our institution. The interval to t-MNs, cytogenetics, response to treatment, and survival were analyzed. The Kaplan-Meier method was used for the estimation of survival. Results: Eleven males and 5 females were identified and their median age was 11.5 y (range, 1.6-20.4). The majority (n=12) of t-MNs was therapy-related acute myeloid leukemia (t-AML) with 3 myelodysplastic syndrome (t-MDS) and 1 chronic myelomonocytic leukemia (t-CMML). The primary malignancy was osteosarcoma (n=3), acute non-myeloid leukemia (n=3), non-Hodgkin lymphoma (n=2), rhabdomyosarcoma (n=2), brain tumor (n=1), Ewing sarcoma (n=1), hepatoblastoma (n=1), synovial sarcoma (n=1), juvenile myelomonocytic leukemia (n=1), or de novo AML (n=1). The median interval from the primary cancer diagnosis to t-MNs was 29 mo (range, 11-68). Fourteen patients (88%) had cytogenetic aberrations, of which 11q23 abnormality was the most frequently observed one (n=8) followed by monosomy 7 (n=3). Of the 13 patients who agreed to treatment with curative intent, 12 patients received myeloid-type induction therapy which led to complete remission (CR) in 8 patients (67%). Except for 4 patients who could not proceed to transplantation due to chemotherapy-related toxic deaths (n=3) or parental refusal (n=1), 9 patients eventually underwent allogeneic transplantation (3 matched-related, 3 matched-unrelated, 3 umbilical cord blood). The 5-y overall survival and event-free survival of 13 patients who received any type of treatment were 30.8% and 61.5%, respectively, with a median follow-up of 105 mo (range, 60-159). For the 9 patients who were transplanted, the 5-y event-free survival was 66.7%. Among the 3 patients whose disease was refractory or relapsed at transplantation, 2 patients survived 89 and 75 mo, respectively, without relapse while no patients survived without transplantation. Conclusions: A significant proportion of children and adolescents with t-MNs can be a long-term survivor, and allogeneic hematopoietic stem cell transplantation seems to have a key role for the cure of these patients.