Borderline personality disorder (BPD) is characterized by interpersonal difficulties, whereby patients are negatively biased concerning the evaluation of others' trustworthiness. Here, we examined the effect of oxytocin on interpersonal behavior of BPD patients in a trust game, emphasizing the assessment of facial attractiveness of the patients' counterparts in the game, and patients' history of childhood trauma. Thirteen BPD patients and thirteen healthy controls played a trust game after receiving oxytocin or placebo in a randomized, double-blind crossover design. Childhood trauma was evaluated using the Childhood Trauma Questionnaire (CTQ). Patients transferred less money in the oxytocin condition compared to placebo. While healthy controls transferred more money units (MUs) to attractive counterparts than to unattractive ones only after the administration of oxytocin, BPD patients showed this pattern in both conditions. Emotional neglect during childhood negatively correlated with the amount of MUs transferred by patients under oxytocin, but not placebo. Oxytocin had a trust-lowering effect in BPD, which was correlated with patients' history of childhood trauma. Patients' evaluation of interpersonal trust seems to depend more on attractiveness features of their counterparts than in controls, a finding that may have important implications for further research on the usefulness of "prosocial" peptides as an adjunct to psychotherapeutic interventions.