The purpose of the study was to test whether aesthetic judgments of music are affected by expertise or harmonic violation of musical sequences. The participants were 14 musical experts and 13 laypersons; they were asked to judge the beauty and correctness of extracts from J. S. Bach's chorales. Experts and laypersons showed different late positive potential (LPP) responses to the appraisal of correctness. LPP also proved to be sensitive to the extent to which the extracts violated harmonic expectations. The relationship between the early right anterior negativity potential (ERAN) and the harmonic correctness of chords was similar in laypersons and experts.