The present study examined the effect of participants' music genre preference on the neural processes underlying evaluative and cognitive judgements of music using the event-related potential technique. To this aim, two participant groups differing in their preference for Latin American and Heavy Metal music performed a liking judgement and a genre classification task on a variety of excerpts of either music genre. A late positive potential (LPP) was elicited in all conditions between 600 and 900 ms after stimulus onset. During the genre classification task, an early negativity was elicited by the preferred compared to the non-preferred music at around 230-370 ms whereas the non-preferred genre was characterized by a larger LPP. The findings suggest that evaluative and cognitive judgements of music are accompanied by affective responses and that the valence of music may spontaneously modulate early processes of music categorization even when no overt liking judgement is required. (C) 2012 Elsevier B.V. All rights reserved.