Background Increased impulsivity is considered to be a core characteristic of borderline personality disorder (BPD) and has been shown to play a significant role in decision making and planning. Neuropsychological studies in BPD revealed impairments of executive functions, and it is assumed that these deficits are related to altered feedback processing. However, research on executive functions in BPD is still limited and the underlying deficits remain an open question. The present study, therefore, explored whether decision-making deficits are related to altered feedback evaluation in BPD.Method A total of 18 BPD patients and 18 matched healthy controls underwent a modified version of the Iowa Gambling Task while an electroencephalogram was recorded. Feedback processing was examined by measuring the feedback-related negativity (FRN) and the P300 as electrophysiological correlates of feedback evaluation.Results Behavioural results revealed that BPD patients, relative to controls, made more risky choices and did not improve their performance. With regard to the FRN, amplitudes in BPD patients did not discriminate between positive and negative feedback information. Further, BPD patients showed reduced FRN amplitudes, which were associated with enhanced impulsivity and enhanced risk taking. In contrast, the P300 amplitudes following negative feedback were increased in BPD patients, relative to controls.Conclusions This study indicates that BPD patients are impaired in decision making, which might be related to a dysfunctional use of feedback information. Specifically, BPD patients did not learn to avoid disadvantageous selections, even though they attended to negative consequences.