Suicidal behavior is frequent in patients with borderline personality disorder (BPD); at least three-quarters of these patients attempt suicide and approximately 10% eventually complete suicide. Borderline patients at greatest risk for suicidal behavior include those with prior attempts, comorbid major depressive disorder, or a substance use disorder. Comorbidity with major depression serves to increase both the number and seriousness of the suicide attempts. Hopelessness and impulsivity independently increase the risk of suicidal behavior, as does a turbulent early life and the presence of antisocial traits. In summary, because BPD is frequently complicated by suicidal behavior, clinicians must avoid the mistake of thinking that a pattern of repeated attempts indicates little desire to die. Clinicians have an important role in preventing suicide attempts and completed suicides by understanding the risk factors.