The early right anterior negativity (ERAN) is an event-related potential (ERP) reflecting processing of music-syntactic information, that is, of acoustic information structured according to abstract and complex regularities. The ERAN is usually maximal between 150 and 250 ms, has anterior scalp distribution (and often right-hemispheric weighting), can be modified by short- and long-term musical experience, can be elicited under ignore conditions, and emerges in early childhood. Main generators of the ERAN appear to be located in inferior fronto-lateral cortex. The ERAN resembles both the physical MMN and the abstract feature MMN in a number of properties, but the cognitive mechanisms underlying ERAN and MMN partly differ: Whereas the generation of the MMN is based on representations of regularities of intersound relationships that are extracted online from the acoustic environment, the generation of the ERAN relies on representations of music-syntactic regularities that already exist in a long-term memory format. Other processes, such as predicting subsequent acoustic events and comparing new acoustic information with the predicted sound, presumably overlap strongly for MMN and ERAN.