Emotion dysregulation is widely believed to be one of the core features of borderline personality disorder (BPD). To date, there has been no study examining psychophysiological and self-report measures of deliberate regulation of emotions in BPD in those in the early phases of the disorder. The aims of the study were to measure the 1) psychophysiological and subjective emotional response and 2) psychophysiological and subjective ability to regulate one's emotional response to emotional images in 15- to 24-year-olds with first-presentation BPD compared with healthy controls. Twenty patients with full-syndrome BPD and 20 healthy comparison participants were examined. Test stimuli used were a set of standardized photographic images with pleasant, neutral or unpleasant valence. Participants were also instructed to either ‘maintain’ or ‘suppress’ the emotional response they were having to the stimuli. In addition to self-report ratings, emotional responses to the stimuli were measured by startle response and skin conductance. Contrary to the hypotheses, self-report and psychophysiological data did not provide evidence that the BPD participants reacted with more intense affective responses to unpleasant stimuli than the control participants. In fact, the BPD participants had significantly lower skin conductance responses and showed an absence of the fear-potentiated startle response, suggesting a general state of underarousal. On the emotion regulation task, both groups showed similar startle responses when instructed to maintain or suppress their emotions. These results do not support current theories of emotion dysregulation in BPD, suggesting instead that those with BPD are hyporesponsive to affective stimuli.