Objective: Compare the processing of music-syntactic irregularities and physical oddballs between cochlear implant (CI) users and matched controls. Methods: Musical chord sequences were presented, some of which contained functionally irregular chords, or a chord with an instrumental timbre that deviated from the standard timbre. Results: In both controls and CI users, functionally irregular chords elicited early (around 200 ms) and late (around 500 ms) negative electric brain responses (early right anterior negativity,ERAN and N5). Amplitudes of effects depended on the degree of music-syntactic irregularity in both groups; effects elicited in CI users were distinctly smaller than in controls. Physically deviant chords elicited a timbre-mismatch negativity (MMN) and a P3 in both groups, again with smaller amplitudes in CI users. Conclusions: ERAN and N5 (as well as timbre-MMN and P3), can be elicited in CI users. Although amplitudes of effects were considerably smaller in the CI group, the presence of MMN and ERAN indicates that neural mechanisms of both physical and music-syntactic irregularity-detection were active in this group.