40Hz event related potentials(ERP) in response to 0.5KHz, 1KHz and 2KHz tone pips were studied in 20 subjects in order to assess their reliability and thresholds in normal adults and to study the effects of stimulus frequency and intensity on their latency and amplitude. In all subjects well formed and reproducible 40Hz ERP were detected, thus showing a good reliability of 40Hz ERP to tone pips. The response showed a sequency of positive(P1, P2) and negative(N1, N2) waves. The interwave latency between the positive(P1-P2) and the negative waves(N1-N2) was about 25ms regardless of stimulus intensity and frequency values. It has also been observed that the latency of the first component following the acoustic stimulus decreased at increasing stimulus frequency and intensity, while the amplitude of the whole response increased upon increasing stimulus intensity. It can be suggested that the 40Hz ERP to tone pips may represent a useful tool in assessing auditory threshold.