Dialectical behaviour therapy (DBT) has proven to be an effective treatment in borderline personality disorder (BPD). However, the effectiveness in BPD of DBT skills training (DBT-ST) alone is not known. This study aimed at comparing the efficacy of DBT-ST and standard group therapy (SGT) for outpatients with BPD. Sixty patients meeting the DSM-IV diagnostic criteria for BPD, as assessed by two semi-structured diagnostic interviews, were included in a 3-month, single-blind randomised controlled trial. A total of 13 weekly group psychotherapy sessions of 120 min of either SGT or DBT-ST were conducted. Assessments were carried out every 2 weeks by two blinded evaluators. Observer-rater, self-report scales and behavioural reports were used as outcome measures. DBT-ST was associated with lower dropout rates, 34.5% compared to 63.4% with SGT. It was superior to SGT in improving several mood and emotion areas, such as: depression, anxiety, irritability, anger and affect instability. A reduction in general psychiatric symptoms was also observed. Three-months weekly DBT-ST proved useful. This therapy was associated with greater clinical improvements and lower dropout rates than SGT. DBT-ST seems to play a role in the overall improvement of BPD seen with standard DBT intervention. It allows straightforward implementation in a wide range of mental health settings and provides the additional advantage that it is cost effective.