Purpose: Considering the complexity and importance of borderline 
personality disorder as well as the relatively high prevalence rate of this 
disorder in the society, this research was conducted as a comparison of the 
effectiveness of emotion- focused therapy with mentalization-based 
therapy on the treatment of people with borderline personality disorder.
Methodology: The method of this semi-experimental research and the 
design used to examine the hypotheses in this research was a pre-test-posttest design with an experimental group and a control group. The statistical 
population of this research consisted of all people with borderline 
personality disorder who visited two counseling centers in Tehran district 
1 in 2019. Therefore 45 people with borderline personality disorder were 
selected by purposive sampling method and then these people were placed 
in three groups of 15 (emotion-oriented treatment experimental group, 
mentalization-based treatment experimental group and control group) by 
matching method. The experimental groups received 12 weekly 120-
minute sessions of emotion-focused therapy and mentalization-based 
therapy, and the control group did not receive therapy. The data collection 
instrument in this research was the borderline personality questionnaire by 
Leishnering (1999). Due to the quantitative nature of the research, data 
analysis was done using descriptive and inferential statistical methods 
(covariance analysis test).
Findings: The findings showed that emotion- focused therapy and 
mentalization-based therapy are effective on the treatment of people with 
borderline personality disorder. Also, the results showed that there is a 
significant difference between the effectiveness of emotion-focused 
therapy and mentalization-based therapy on the treatment of borderline 
personality disorder, and the effectiveness of mentalization-based therapy 
is greater than emotion-focused therapy on the treatment of borderline 
personality disorder.
Conclusion: Both intervention methods were effective in improving the 
symptoms of people with borderline personality disorder. However, the 
effect of mentalization-based therapy is more effective than emotionfocused therapy the treatment of people with borderline personality 
disorder.