There are hints for a negative predictive power of dissociative states for treatment outcome in patients with borderline personality disorder. A possible explanation is the alteration of information processing associated with dissociation. Dissociative states can be influenced by specific psychotherapeutic interventions. 30 patients with borderline personality disorder were assessed with self-report questionnaires to evaluate dissociation and psychopathology before and after treatment with Dialectic Behavior Therapy. As found in recent studies, dissociation before treatment was correlated to general psychopathology at treatment end. In contrast to the core hypothesis, patients with high initial dissociation did not present less improvement than those with lower initial degrees regarding the parameters of general psychopathology, anxiety, depression and psychosocial functioning. In terms of the parameter of dissociation, patients with high degrees of initial dissociation even achieved the highest extent of relative symptom reduction. This astonishing result can be explained by the treatment setting which to a high extent provided specific psychoeducation and treatment concerning dissociative behavior.