Borderline personality disorder is a severe disorder that increases disability to a considerable extent. Emotional instability, difficulties in regulating behavior and interpersonal relationships are essential features of the disorder. Borderline personality disorder has a more favorable course than previously thought. Dialectic behavioral therapy, cognitive therapy, mentalization therapy and transference-focused psychotherapy seem to be effective. Hospital treatment should be carried out primarily in day hospital settings. Antipsychotics and mood stabilizers may be used for a range of symptoms. SSRIs may be useful in the treatment of impulsivity and aggression. Benzodiazepines should be avoided.