Dialectical behaviour therapy (DBT) is a recommended treatment of patients with borderline personality disorder, yet there are few descriptions of the approach in public community mental health settings where the majority of such patients present. This study describes the development and evaluation of a DBT programme in an Irish setting. The DBT programme was run over a six month period. Participants were assessed at baseline and post intervention with the following instruments: The Structured Clinical Interview for DSM III R personality disorders (SCID II), the clinical Outcomes in Routine Evaluation (CORE) and the symptom checklist 90 Revised (SCL-90-Revised). Inpatient bed usage was determined from case note review. Outcome data was available for eight subjects. Significant improvement (p < 0.005) was seen on all CORE subscales. SCL-90-R showed significant improvement (p < 0.05) on the global severity index and on the positive symptom distress index. A decrease in self harming behaviour was found. Subjects' inpatient bed days dropped from a mean of 58 in the year pre intervention to a mean of four days in the year post intervention. A novel finding was that 43% of subjects who originally fulfilled criteria for avoidant personality disorder no longer did so post intervention. The study found that DBT can be applied in a community mental health setting with benefits similar to more specialist settings. Significant difficulties were encountered in implementing the programme. The clinical implications are that specialist psychotherapy services need to be an integral part of psychiatric services to achieve better outcomes for patients with borderline personality disorder.