Effect of age on P300 wave

30 healthy elderly males (mean age 77.4 +/- 4.3 yrs) were subjects in this study. Equal number of young males (mean age 22 +/- 3.5 years) and middle aged subjects (mean age 46 +/- 3.2 years) served as control. P300 wave was estimated using a Neuropack 4 model of Nihon Kohden EMG machine. We observed a significantly increased latency, poorly defined and non reproducible P300 wave in 90% old subjects while in young the latency was in normal limits and the wave was well defined and reproducible. We presume P300 could serve as a future potential marker of the neurophysiological basis of aging.