边缘性人格疾患（Borderline Personality Disorder，缩写：BPD）又称情绪不稳定人格障碍，简称边缘人格ICD-10，是一种B型人格疾患。它的主要特征是精神上，行为上的极端对立表现的同时出现。边缘人格因介于健康、忧郁症、精神官能症、精神病这四者之间的边缘，故称为边缘人格。他们和一般人一样拥有健康的部分，因容易遇到一点小事就感到受伤，无法控制冲动的欲望，作出自我伤害、伤害他人……等破坏性的行为，且这些行为会反复出现。其他症状可能包括当面临着一个时间有限的分离情况，会出现强烈的被抛弃恐惧感、绝望和不恰当的愤怒。

Borderline personality disorder (BPD) is a pattern of abnormal behavior characterized by extreme fears of abandonment, unstable relationships with other people, sense of self, or emotions, feelings of emptiness, frequent dangerous behavior, and self-harm. Symptoms may be triggered by seemingly normal events. This pattern of behaviour typically begins by early adulthood, and occurs across a variety of situations . People with BPD often engage in idealization and devaluation of others, alternating between high positive regard and great disappointment. Substance abuse, depression, and eating disorders commonly co-exist with borderline personality disorder. About 6% die by suicide.