Concurrent personality disorder (PD) and substance use disorder (SUD) are common in clinical practice. However, SUD is the main criterion for study exclusion in most psychotherapeutic studies of PD. As a result, data on treatment outcomes in patients with concurrent PD/SUD are scarce. The study sample consisted of 51 patients diagnosed with severe PD and admitted for psychotherapeutic treatment as a part of routine mental health care. All patients were diagnosed with PD according to the Structured Clinical Interview for PD. Patients were further assessed (DSM-IV diagnostic criteria) to check for the presence of concurrent SUD, with 28 patients diagnosed with both disorders (PD-SUD). These 28 cases were then compared to the 23 patients without SUD (PD-nSUD) in terms of psychiatric hospitalizations and psychiatric emergency room (ER) visits before and during the 6-month therapeutic intervention and every 6 months thereafter for a total of 36 months. The baseline clinical characteristics correspond to a sample of PD patients (78% met DSM-IV criteria for borderline PD) with poor general functioning and a high prevalence of suicide attempts and self-harm behaviors. Altogether, the five outcome variables - the proportion and the number of psychiatric inpatient admissions, the number of days hospitalized, and the proportion and the number of psychiatric ER visits - improved significantly during the treatment period, and this improvement was maintained throughout the follow-up period. Although PD-SUD patients had more psychiatric hospitalizations and ER visits than PD-nSUD patients during follow-up, the differences between these two groups remained stable over the study period indicating that the treatment was equally effective in both groups. Specialized psychotherapy for severe PD can be effectively applied in patients with concurrent PD-SUD under usual practice conditions. These findings suggest that exclusion of patients with dual disorders from specialized treatments is unjustified.