Using ERP measures, the present study investigated the neural mechanism of the interaction between trait aggression and neural sensitivity to unpleasant stimuli. Event-related potentials (ERPs) were recorded for pleasant and unpleasant stimuli when subjects were required to categorize the emotion of stimuli. The ERP result showed a significant interaction between aggression and emotion during 450-600 ms interval. Unpleasant stimuli elicited more pronounced positive deflection than pleasant stimuli in low aggressive subjects whereas this was not observed in high aggressive subjects. This suggests that trait aggression influences the neural sensitivity to unpleasant stimuli.