Somatosensory evoked potentials(SEPs) are useful for the evaluation of the nervous system from peripheral receptor to cerebral cortex.

SEPs were recorded from 46 normal subjects (male=28, female=18), aged 15∼70 years(mean=41.9) using TECA 42 EMG system. Both median nerves were stimulated at wrist and recording electrodes were placedon C₂(active) and Fz(reference) position of the international 10-20 EEG system. Following results were obtained.

1) The mean latencies of the No, N₁, P₁, N₂, P₂ were 15.4±0.97 msec, 18.7±0.91 msec, 23.5±1.76 msec, 31.7±2.25 msec, 42.6±3.02 msec respectively on the right side.

2) The mean amplitudes, N₁P₁ and N₂P₂ on the right side were 8.06±1.61㎶ and 5.85±1.90㎶ and NP/NP was 72.5%.

3) The N₃ was neglected due to irregularity and inconsistency in shape.

4) Difference between the right and left and between the male and female for the latency and amplitude were not found, but N₂P₂/N₁P₁ of the male and female respectively were 79.8% and 67.9% on the right side.

5) According to aging, mean latencies were increased.