Objective There have been many biological studies on suicide behaviors of borderline personality disorder (BPD), however few studies have sought to psychoanalytic characteristics including defense mechanisms. Therefore, we investigated psychological, symptomatic, and personality characteristics including defense mechanisms in suicide attempters and non-suicide attempters among patients with BPD. Methods We enrolled 125 patients with BPD. Forty-two patients with a history of one or more suicide attempts formed the suicide attempters group and 83 patients with no such history formed the non-suicide attempters group. We collated the differences in clinical and psychological characteristics between the two groups by using the Symptom Checklist-90-Revised (SCL-90-R), the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), the Personality Disorder Questionnaire-4+ (PDQ-4+), and the Defense Style Questionnaire (DSQ). Results The suicide attempters group scored higher on the hostility subscale of SCL-90-R. The suicide attempters group also scored higher on the Infrequency, Back Infrequency, Lie, Masculinity-femininity, Paranoia, Psychasthenia, and Schizophrenia scales of the MMPI-2. The incidence of paranoid and antisocial personality disorders, as assessed by the PDQ-4+, was significantly different in both groups. Maladaptive, self-sacrificing defense style, splitting and affiliation on the DSQ were also higher for the suicide attempters group. In the results of the logistic regression analysis, gender, the F(B) and L scales on the MMPI-2, and ‘splitting of other’s image’ defense mechanism on the DSQ were the factors that significantly influenced to suicide attempts. Conclusion These findings suggest that impulsive psychiatric features and maladaptive defense style may be related to suicidal risk in patients with BPD. Therefore, our findings may help clinicians in estimating the risk of suicide in patients with BPD.