Dialectical Behavior Therapy (DBT) has been proposed as a useful treatment for a wide range of clients with symptoms functionally similar to those of Borderline Personality Disorder (BPD), having in common pervasive emotion dysregulation. There is a set of personality disorders belonging to cluster C (DSM-IV-TR, APA, 2000) that represent the dialectical opposite of BPD and related disorders. These disorders are characterized also by difficulties in emotion regulation: being emotionally constricted, overcontrolled, cognitively rigid, and behaviorally avoidant; and include obsessive-compulsive personality disorder (OCPD) and avoidant personality disorder (APD). These features are opposite to the features of BPD (i.e., emotional constriction vs emotional dysregulation, overcontrolled behavior vs impulsive behavior, etc.). DBT could be a useful approach for the treatment of these disorders, given that its main target are emotion regulation difficulties. In this work we present preliminary findings of the efficacy of a six-month DBT-based program for the treatment of four patients with a diagnosis of cluster C personality disorder. Our findings showed a significant improvement in depression, anger, perceived anxiety control, and global functioning.