Background: Few studies have examined deliberate self-harm (DSH) among children in residential treatment in Canada. Most of the existing studies examined adolescent students or children from pediatric emergency departments. Objectives: The objectives of this study were to examine the prevalence of DSH among children in tertiary care residential treatment and the factors associated with DSH. Methods: Data on 284 children aged 5-17 years (M = 11.54 years, SD = 2.56) with mental health problems in tertiary care residential treatment were analyzed. Binary logistic regression was performed to examine the likelihood of engaging in DSH. Results: About 35 % of children engaged in DSH. Suicidal talk emerged as the strongest factor to be associated with DSH. Children who used alcohol or drugs were also more likely to engage in DSH than those who did not use alcohol or drugs. Furthermore, symptoms of conduct problems were associated with the likelihood of engaging in DSH. Conclusions: Identifying children at risk for engaging in DSH and suicidal behavior is of critical importance to mental health care providers. These factors could assist in identifying children who might require more specialized treatment related to self-harm during their stay in residential treatment.