To examine the potential role of ovarian hormones in biological vulnerability to borderline personality disorder (BPD). The review focuses primarily on research examining the menstrual cycle as a source of short-term lability of BPD symptom expression, while discussing the currently understudied possibility of ovarian hormone influence in the developmental course of BPD.Several patterns of menstrual cycle effects on BPD symptoms and relevant features in non-clinical samples have been observed in empirical studies. Most symptoms demonstrated patterns consistent with perimenstrual exacerbation; however, timing varied between high and low arousal symptoms, potentially reflecting differing mechanisms. Symptoms are typically lowest around ovulation, with an exception for proactive aggression and some forms of impulsive behaviors. Preliminary evidence suggests ovarian hormones may exert strong effects on BPD symptom expression, and further research is warranted examining mechanisms and developing interventions. Recommendations for researchers and clinicians working with BPD are provided.