This study examined the dissociative comorbidity reported by psychiatric inpatients with and without borderline personality disorder. The Dissociative Disorders Interview Schedule and Dissociative Experiences Scale were administered to 201 general adult psychiatric inpatients; of these, 110 also received the Structured Clinical Interview for DSM-IV-TR Dissociative Disorders. The patients were then divided into two groups--a group of 93 who met criteria for borderline personality disorder on the Dissociative Disorders Interview Schedule and 108 who did not. The two groups were then compared on dissociative symptoms and disorders. The inpatients with borderline personality disorder reported significantly more dissociative symptoms and disorders on all measures. On the Dissociative Disorders Interview Schedule, 59% of the borderline patients met criteria for a dissociative disorder compared with 22% of the non-borderline patients. Chronic, complex dissociative symptoms and disorders are common in borderline personality disorder. The ninth DSM-IV-TR criterion for borderline personality disorder does not adequately describe the dissociative comorbidity in the disorder.