Objective: Evidence-based therapies for borderline personality disorder (BPD) are lengthy and scarce. Data on brief interventions are limited, and their role in the treatment of BPD is unclear. Our aim was therefore to evaluate the clinical effectiveness of brief dialectical behaviour therapy (DBT) skills training as an adjunctive intervention for high suicide risk in patients with BPD. Method: Eighty-four out-patients were randomized to 20 weeks of DBT skills (n = 42) or a waitlist (WL; n = 42). The primary outcome was frequency of suicidal or non-suicidal self-injurious (NSSI) episodes. Assessments were conducted at baseline 10, 20 and 32 weeks. Results: DBT participants showed greater reductions than the WL participants on suicidal and NSSI behaviours between baseline and 32 weeks (P < 0.0001). DBT participants showed greater improvements than controls on measures of anger, distress tolerance and emotion regulation at 32 weeks. Conclusions: This abbreviated intervention is a viable option that may be a useful adjunctive intervention for the treatment of high-risk behaviour associated with the acute phase of BPD.