Introduction. The incidence growth of the cardiovascular disease associated with psychiatric pathologies has led to increased attention on the autonomic nervous system. Heart rate variability (HRV) is considered as a measure of autonomic nervous system balance, and therefore it may provide a quantification of the physiological changes associated with mental illness. HRV cut is associated with a variety of psychological conditions and dimensions such as social status, executive function and emotional regulation. Borderline personality disorder (BPD) with a high rate of cardiovascular mortality, it is also characterized by emotional instability, which makes it ideal for studying heart rate variability. Aim of the study. The purpose of the study is to determine autonomous changes to people with borderline personality disorder by studying the variability of the heart rate both during the break and in the pain test. Materials and methods. The study was performed on 103 people, psychometric test, which preceded the recording of cardiac parameters, was realized with the help of the Personality Disorders Test (PDT) (Personality Inventory for DSM-5, PID-5). Thus, based on the results obtained from the PID-5 test, people were divided into 2 groups, the first-control group - 69 people (N = 69), the second group BPD- 34 people (N = 34). The protocol of the experiment included the recording of the electrocardiogram using the computer system Biopac MP-36 during the break repose (R) - for 5 minutes; Pain test (P) - 3 min; post-pain (pP) -5 minutes. The primary data processing was performed using the program "Kubios HRV Standard (version 3.2.0, 2019). Results. The HRV parameters of the spectral analysis (Fourier), including the LF components, the low frequency spectral variation as an index of the sympathetic modulation and the HF the high frequency spectral variation as a primary factor in the evaluation of the vagal activity, do not show significant differences between the both groups included in the study. Within the second group, in pP the low frequency (LF) increase with 16.3% in pP compared to R, (p <0, 01) and with 12% (p <0.05), compared to P. This denotes a tendency towards dynamic emphasis on the sympathetic vegetative nervous system activity. Dynamic evaluation of the average values of the high spectral frequency (HF) variation is lower with 15.5% in pP than R (p <0.01); and with 13% lower pP compared to P test,( p <0.05). Conclusions. The differences between the HRV parameters in the second group recorded in the functional tests could probably be explained by the high activity of the structures involved in the affective control of pain in people with borderline personality disorder.