Dissociative symptoms including flashbacks, i.e. vivid scenic recollections of traumatic episodes, in patients with Borderline Personality Disorder are a serious and often treatment-refractory problem. There is evidence suggesting changes in endogenous opioids in patients with Borderline Personality Disorder. Naltrexone, an opioid receptor antagonist, was administered to three female patients with Borderline Personality Disorder in a dosage of 50 mg (q.i.d.,p.o.) over several weeks. We observed a marked reduction in dissociative symptoms.