The present study examined the effect of the presence of borderline personality disorder characteristics (BPC) on patients' responses to cognitive behavioral treatment for chronic PTSD. Seventy-two female victims of sexual and non-sexual assault were randomly assigned to one of four treatment conditions: prolonged exposure (PE), stress inoculation training (SIT), combined treatment (PE/SIT), and wait list control (WL). Treatment consisted of nine bi-weekly individual sessions. Seventeen percent of the patients met full (10%) or partial criteria (7%) for borderline personality disorder. A greater number of patients with BPC reported sexual assault in childhood compared to those without the symptomatology. Patients with BPC also reported more pre-treatment anger. In general, those with BPC benefited significantly from treatment, although at post-treatment, they were less likely to achieve good end-state functioning than those without such symptomatology. The relationship between BPC and treatment response will be discussed.