Chronic pain has a high comorbidity with borderline personality disorder. The aim of this study was to apply and evaluate the effectiveness of the Mindfulness-Based Stress Reduction (MBSR) program in a group of patients with both diagnoses. Twenty-four patients participated, with a mean age of 41.83 years (SD= 10.35), and a majority women (91.7%). The program consisted of eight sessions in which training in mindfulness is central, and was developed through formal practices (yoga, sitting meditation) or informal practices (mindfulness in activities of daily life) in which attitudes as acceptance and openness were promoted. In addition to the post-intervention evaluation, a 9-month follow-up was performed. The results showed improvements in the intensity and interference of pain, anxiety, some coping strategies (cognitive reappraisal, distraction, and mental self-control), mindfulness and quality of life. These results suggest the efficacy of the MBSR program in these patients.