Objective: In order to assess costs - consequences of dialectal behavioural therapy (DBT) in suicidal women with borderline personality disorder (BPD), the present study takes advantage of pilot data collected during a training phase, in relation to a large scale randomised controlled trail (RCT). Method: Under a 18 month period, 22 suicidal women with BPD were treated with outpatient DBT, with focus on reducing parasuicidal behaviour. Outcome data collected retrospectively 12 months before therapy start, were compared to prospective data collected up to 18 months in therapy. The cost - analysis included direct health care costs only. Results & Conclusions: The results suggest that DBT may have a positive impact on treatment costs, which decreased significantly during the last 12 months in a 18 month therapy period. The reduction of costs is due to decrease in the number of psychiatric inpatient days. The conclusions that can be drawn from the results are, however, limited as the study was not made in RCT conditions and indirect costs to society were not assessed.