Adult patients with borderline personality disorders (BPD) frequently have attachments to inanimate transitional objects (TOs) such as stuffed animals. Using event-related potential (ERP) recordings, we determined in patients with BPD the neural correlates of the processing of these attachment-relevant objects and their functional significance. Sixteen female patients with BPD viewed pictures of their TOs, other familiar stuffed toys (familiar objects, FOs), and unfamiliar objects (UOs). ERPs in the patients were compared to those in 16 matched healthy controls who possessed a stuffed animal of comparably high familiarity. Here, we found a specific increase of frontal P3/LPP amplitude in patients with BPD, which was related to attachment anxiety and depression scores. Attachment-related TO stimuli in patients with BPD specifically modulated stages of emotional stimulus evaluation reflecting processing of self-relevance. The relation of the frontal ERP effect to patients' attachment anxiety and depression highlights the function of TOs for coping with anxiety about being abandoned by significant others and for dealing with depressive symptoms.