Cognitive evoked potential is a series of waves made by endogenous brain response following a cognitive stimulus. There are several kinds of waves such as N1, P2, N2, P3 and slow waves and only P3 wave is clinically applicated widely. It is important, however, to set a standard for normal latency of P3 wave because of its wide variation especially according to age.

We studied 93 normal Koreans using auditory odd-ball paradigm and got the following conclusions about the latencies of P3 waves and its relation to age.

1) The range of latency was between 264 and 446 ms, and the average latency was 343,4±37.6 ms.

2) The average latency was decreased by 9.93 ms/year in the below 15 years of age group, but increased by 1.21 ms/year in the above 19 years of age group.

3) The latency was decreased dramatically in both groups of below 10 years and above 60 years of age.