Background: Several studies report associations between adults with borderline personality disorder (BPD) and a history of attention-deficit hyperactivity (ADHD) symptoms in childhood. Aims: To explore the association between BPD and a history of ADHD in childhood. Method: A comprehensive search of EMBASE, PsychInfo and Medline and hand-searching yielded 238 "hits". Fifteen articles were found to have sufficient quality and relevance to be included in the final review. The data were considered in six possible explanatory psychopathological models of the association between ADHD and BPD. Results: Most of the 15 articles showed a statistical association between ADHD and BPD. The data, most strongly provided a basis for the hypotheses that ADHD is either an early developmental stage of BPD, or that the two disorders share an environmental and genetic aetiology. Furthermore, one of the disorders seems to give a synergic effect, reinforce the other or complicate the disorders. In one prospective study, the risk factor for children with ADHD to develop BPD was as high as odds ratio 13.16. No studies have looked at treatment of ADHD as a mediator of the risk for BPD. Conclusions: Many studies pointed at shared aetiology or the risk for development of one disorder, when the other disorder is present. The data do not evaluate how treatment factors or other factors mediate the risk or how overlap of diagnostic criteria adds to the statistical association. More research is much needed, in particular studies looking at early intervention and which treatment of ADHD that might prevent later development of BPD.