Medial frontal scalp-recorded negativity occurring ∼200-300 ms post-stimulus [known as feedback-related negativity (FRN)] is attenuated following unpredicted reward and potentiated following unpredicted non-reward. This encourages the view that FRN may partly reflect dopaminergic 'reward-prediction-error' signalling. We examined the influence of a putatively dopamine-based personality trait, extraversion (N = 30), and a dopamine-related gene polymorphism, DRD2/ANKK1 (N = 24), on FRN during an associative reward-learning paradigm. FRN was most negative following unpredicted non-reward and least-negative following unpredicted reward. A difference wave contrasting these conditions was significantly more pronounced for extraverted participants than for introverts, with a similar but non-significant trend for participants carrying at least one copy of the A1 allele of the DRD2/ANKK1 gene compared with those without the allele. Extraversion was also significantly higher in A1 allele carriers. Results have broad relevance to neuroscience and personality research concerning reward processing and dopamine function.