Dialectical-Behavioral Therapy for Borderline Personality Disorder (DBT) developed by M. Linehan is specifically designed for the outpatient treatment of chronically suicidal patients with borderline personality disorder. Research on DBT therapy, its course and its results has focused to date on treatments in an outpatient setting. Hypothesizing that the course of therapy could be accelerated and improved by an inpatient setting at the beginning of outpatient DBT, we developed a treatment program of inpatient therapy for this patient group according to the guidelines of DBT. It consists of a three-month inpatient treatment prior to long-term outpatient therapy. In this pilot study 24 female patients were compared at admission to the hospital, and at one month after discharge with respect to psychopathology and frequency of self-injuries. Significant improvements in ratings of depression, dissociation, anxiety and global stress were found. A highly significant decrease in the number of parasuicidal acts was also reported. Analysis of the average effect sizes shows a strong effect which prompts the development of a randomized controlled design.