In terms of object relations theory, borderline personality disorder (BPD) is characterized by a structural abnormality of identity, conflicting representations of self and others, and disorganization of attachment – a construct rooted in an individual’s early experiences and central to the relationships established later in life. A special role in the formation of attachment style is attributed to the relationship with the caregiver and to difficult experiences or traumas from early developmental stages. These experiences not only provide the psychological basis for the development of an insecure attachment style, but also leave a biological mark in the body in the form of epigenetic modifications. Although research on epigenetic modifications in BPD is scarce, a growing body of evidence supports the importance of oxytocin – the “social peptide” underlying attachment – in the etiology of BPD. We believe that the study of epigenetic modifications that affect the action of oxytocin in the BPD clinical population will provide a better understanding of the basis and process of development of the disorder, as well as provide a therapeutic direction to work effectively in the major areas of BPD.