THE purpose of this study was to test the previous report that generation of the mismatch negativity (MMN) component of event-related brain potentials (ERPs) is indifferent to the predictable occurrence of stimulus deviance. A pattern of standards (S) and deviants (D) were delivered in a predictable fashion (SSSSD) at two different speeds (1.3 s and 100 ms). An MMN was obtained to the D position tone at the slow but not the fast pace. These results demonstrate that, unlike the P3 component, the MMN is sensitive to the predictable occurrence of stimulus deviance when the predictability can be detected by the brain within the estimated limits of sensory memory.