Aim. The aim of the researches was to inspect the relation between borderline personality and Machiavellianism as well as the tendency to apply various manipulation tactics in everyday life and in therapy. Method. The test used an original/authors' survey for testing the tendency to employ manipulation tactics as well as a MACH-IV questionnaire (Christie, Geis, 1970) for measuring Machiavellianism. The studied group included 30 patients with diagnosed BPD, 37 therapists and 30 persons in the control group. Results. No differences were noted in the general indicator of Machiavellianism; however, the patients scored lower on the Tactics scale than people from the control group. Patients preferred employing the tactics of taking offense, lying and begging in everyday life. Compared to people from the control group, patients presented a larger tendency to employ tactics of begging, threatening and threatening to break off a close relationship, and a lower tendency to employ seduction. According to therapists, during the therapy patients most often resorted to lying and arousing guilt. Therapists assessed the patients' tendency to employ manipulation tactics higher than the patients themselves. Conclusions. BPD patients are characterized by a degree of Machiavellianism similar to that present in people from the control group. Patients show larger tendency to employ tactics of threatening and begging than the people from the control group. Compared to assessments made by doctors and therapists, they lower their own assessment of the tendency to employ manipulation. The longer the seniority of therapists and the larger the number of treated BPD patients, the higher the ability to perceive the patients' tendency to manipulate.