Mismatch negativity (MMN) event-related brain potential reflects the brain's automatic auditory change detection mechanism that depends on integrity of the auditory sensory memory. We studied MMN in easily distractible (n = 20) and in non-distractible (n = 20) healthy 9-year-old children. Two MMN phases were revealed in both groups: an earlier MMN peak at approximately 220 ms and a later negative slope approximately 300-500 ms after stimulus presentation. The results suggested a strong frontal lobe contribution in the generation of the later MMN phase, and this response was significantly reduced in amplitude in the distractible children. The present findings suggest that distractible children may have deficits in the frontally mediated aspects of auditory sensory memory.