Recent neuroimaging studies have suggested that prefrontal cortical regions are involved in the neural control of deception. However, to overcome the correlative restrictions of these studies (Karim et al., 2006; Karim et al., 2009) have investigated the effects of modulating cortical excitability by transcranial direct current stimulation (tDCS) and have shown that inhibition of the frontopolar cortex (BA9/10) can facilitate skillful lying and decrease skin conductance response (SCR) and feelings of guilt while deceiving an interrogator of a mock crime. Whereas these findings support the hypotheses that a dysfunction of BA9/10 may underlie certain psychopathic symptoms characterized by the lack of feelings of guilt and the absence of sympathetic arousal during deception, the relationship between the frontopolar cortex and psychopathic personality traits remain elusive. We report here for the first time that psychopathic personality traits modulate the effects of frontopolar tDCS on deceptive behavior and SCR. Twenty-one volunteers participated in a thief role play in which they were supposed to steal money and then to attend an interrogation with the Guilty Knowledge Test. Psychopathic traits were assessed using the Psychopathic Personality Inventory (PPI). Remarkably, the only PPI-factor showing a significant correlation with SCR during deception was machiavellian egocentricity (ME) which assesses narcissistic and ruthless attitudes in interpersonal functioning. Moreover, only in subjects with low ME, inhibition of the frontopolar cortex led to a significant reduction of SCR and feelings of guilt. However, in subjects with high ME, inhibition of the frontopolar cortex showed no effects. The combination of transcranial cortex stimulation with psychophysiological data and personality factors is a novel approach that might provide important insights into the neurobiology of deception and the pathophysiology of psychopathic traits.