The possible value of event-related potentials (ERPs) in the differential diagnosis of dementia was investigated in a group of 42 demented elderly patients, 29 non-demented elderly patients, and 10 healthy young controls. The auditory evoked potentials were elicited by using target and non-target auditory stimuli. There was no significant difference in N100 and P200 latency between these groups. Our results indicate an age-related increase of P300 latency of 0.3 msec/year in the non-demented subjects. There was no significant difference in P300 latency between demented and non-demented patients, and the latencies vary widely within the groups of elderly patients.