Down syndrome (DS), the most common syndromic chromosomal abnormality is associated with a unique susceptibility to develop both acute myeloid (ML) and lymphoblastic leukaemia (ALL). These leukaemias differ from the non-DS-related types of leukaemia and are thought to be distinct biological entities.To perform a retrospective review of our experience of treating DS-related leukaemia at Our Lady's Children's Hospital.Data were extracted from a database established in 2000 to prospectively gather data on DS-associated leukaemias and their outcomes following polychemotherapy. Kaplan-Meier survival curves were constructed.Nineteen patients with DS-ML were treated and 19 with DS-ALL. Sixteen (84%) patients with DS-ML are alive and in complete remission with a median follow-up of 7 years. All deaths in this cohort were due to treatment-related mortality (TRM). Of the DS-ALL patients, 12 (63%) remain alive with a median follow-up of 3.6 years. TRM accounted for five of the six deaths. One death was due to leukaemic relapse.High cure rates are seen in DS-ML using contemporary polychemotherapy protocols, however, there is significant TRM in this cohort. DS-ALL does not have the same high cure rate as non-DS-ALL (>90%) and again this is mainly due to an excess of TRM.