Summary Dialectical Behavioral Therapy for Male Adolescents with Borderline Symptomatology The efficacy of Dialectical Behavior Therapy for adolescents (DBT-A) in patients with borderline symptomatology has mainly been shown in female adolescents. However, male adolescents with borderline symptoms are characterized by more aggressive, disruptive, and antisocial behavior. Therefore, the efficacy of the DBT-A has to be investigated in male adolescents. The DBT-A manual was adopted for male adolescents in an inpatient setting. The program has been investigated using a pre-post design in seven male adolescents (on average 14 years of age) with an average of five borderline symptoms according to DSM-IV. Criteria for outcome are symptoms of psychopathology, emotion regulation, aggressive, and self-injurious behavior. After treatment a reduction in aggressive behavior (pre-post effect size d = 1.18) and an improvement in adaptive emotion regulation (d = 0.65) were shown. No improvement could be shown in general symptoms of psychopathology (d = 0.02). The results of these case studies of DBT-A in male adolescents are promising. However, further RCTs with larger sample sizes and a control group will be required.