The last ten years have evidenced a rapidly growing body of empirical research on the validity of borderline personality disorder (BPS). Since its operationalization by Gunderson and the DSM-III, doubts have been raised to the validity of BPD as a separate diagnostic enitity. BPD had been described as an atypical or subclinical affective disorder, a schizophrenia spectrum disorder, an organic brain syndrome and a post-traumatic stress disorder.

The present paper presents a systematic evaluation of the empirical findings regarding the distinctiveness of BPD and affective disorders. It is concluded that BPD is not a subaffective disorder, but a separate diagnostic entity outside the affective spectrum. Future research should focus on the relationship between BPD on the one hand and impulse control disorders and early childhood trauma on the other.