Objective: To study the effect of age, gender, head size on patternreversal VEP. Method: Studies were conducted on 167 healthy adult volunteers (96 women, 71 men). The entire stimulating field subtended an angle of 16 degrees; each individual square of the checkerboard subtended 15, 30, or 60 minutes of arc measured to the eye. The subject was seated on a chair 127 cm from TV screen. Screen luminance was 25 luxes; background luminance was 15 luxes. VEPs were obtained by a stimulation frequency of a pattern reversal every 1 sec. Each evoked potential was the result of the summation of 60 responses. Midoccipital electrode was placed 5 cm above the inion, and was referred to a midfrontal reference electrode 12 cm above the nasion. We measured each peak latency of P50, N75, P100, and N145, and peak-to-peak amplitude of P50-N75, N75-P100, and P100-N145. Three way ANOVA was used to evaluate the effects of age, gender, head size on pattern-reversal VEP latency and amplitudes. Result: The age influenced each peaks latency. The checksize influenced each peak latency and amplitude (P50-N75, N75-P100). The smaller the checksize was, the larger both the latency and amplitude were. The gender each peak latency and each peak-to-peak amplitude. Latency was shorter and amplitude was larger in women than in men. The head size did not influence VEPs. Conclusion: Pattern VEP latencies are influenced by age, gender, and checksize. Pattern VEP amplitudes are influenced by gender and checksize. are influenced by gender and checksize.