In the current ERP study, an active oddball task was carried out, testing pure tones and auditory, visual and audiovisual syllables. For pure tones, an MMN, an N2b, and a P3 were found, confirming traditional findings. Auditory syllables evoked an N2 and a P3. We found that the amplitude of the P3 depended on the distance between standard and deviant. A smaller distance required more attention, which was reflected in a larger amplitude. An analysis of audiovisual material, after correction for visual activity, showed that McGurk type stimuli evoked brain responses that differed from both the standard and the congruent deviants. Finally, we found that congruent audiovisual stimuli elicited an N2 with a shorter latency and a P3 with a smaller amplitude than auditory stimuli. The current ERP study, thus, shows that for audiovisual processing the whole is more than the sum of its parts. (Contains 1 table and 7 figures.)