Dialectical behaviour therapy (DBT) is a psychotherapeutic intervention that was designed specifically to treat deliberate self-harm (with or without suicide intent) in women with borderline personality disorder (BPD). DBT has received the most research attention compared with other psychological approaches used in the management of symptoms of BPD. This article provides a commentary on a meta-analysis of 11 randomised controlled trials (RCTs) that investigated the effects of DBT on self-harming behaviours and negative emotions in patients with BPD. The commentary includes a critical appraisal of the methodology used in the meta-analysis. The authors of this article conclude that although the meta-analysis provides some evidence that DBT may reduce self-harming behaviours and depression in individuals with BPD, its methodological limitations, and the high risk of bias identified within the RCTs reviewed, mean that the results should be viewed with caution.