This investigation examined the cortical somatosensory-evoked potentials (SEP) waveforms obtained from four sets of commercially available subdermal needle electrodes in 19 normal subjects. The composite materials of the four electrodes were stainless steel and a platinum/iridium alloy. Tibial nerve SEP peak latencies for P37 and N45 as well as P37/N45 amplitudes were recorded from each electrode pair in a random fashion. Using nonparametric analysis, no significant differences of waveform parameters were found between electrode pairs (P greater than 0.01). Correlation evaluation demonstrated values in excess of 0.92. Additionally, intertrial waveform analysis for each of the electrode pairs was performed. Again, nonparametric evaluation demonstrated no statistically significant waveform differences. Correlation coefficients were also highly correlative. Variable temperature response to prolonged tibial nerve stimulation was recorded that did not significantly effect the latencies or amplitudes of the cortical SEP responses. We conclude that within temperature ranges typically encountered in clinical practice, there is no statistically significant waveform differences recorded with commonly available subdermal needle electrodes. Additionally, although intertrial waveform variation may exist during SEP recordings, these differences do not reach statistically significant levels.