- Background: Adults with Borderline Personality Disorder (BPD) manifest poor performance on tasks of decision making which may be congruent with their decisional and interpersonal conflicts in real life. Poor decision making is often assumed to be due to impulsive behaviour or weak inhibitory control despite inconsistent evidences of these relationships, leaving questions about the specific nature of these decisional deficits. Decision making in BPD may be compromised by different domains of impulsivity, affective dysregulatory processes or unknown co-morbid ADHD which is considered a developmental precursor to BPD. Findings: Iowa Gambling Task (IGT) decision making, 2 tasks of inhibitory control and a self report of ADHD symptoms consisting of 9 subscales were administered to 41 BPD women and 41 healthy controls. No group differences in inhibitory control were present. Net decision making performance and all ADHD subscale ratings differed significantly among BPD women and healthy controls. BPD women did not meet the threshold indicative of moderate to severe ADHD. Three subscales of attention, behaviour/ disorganized and emotive were significantly associated with poor IGT performance in 26 women with BPD. Of these 3 variables, the emotive subscale, representing a rapid emotional response, was the only significant predictor contributing 49% to the variance in poor DM. Conclusions: This is the 1st evidence of an emotive type of impulsivity, representing a type of affective instability that is linked to poor IGT DM in BPD. Findings support the Somatic Marker Hypothesis of IGT DM and may reflect the affective dysregulation that characterizes the disorder.