Abstract Objective To investigate whether differences in visual evoked potential (VEP) latencies in a large sample of healthy subjects are influenced by different head size or sex or both. Methods Black-and-white pattern-reversal checkerboard VEPs at a frequency of 2 c/deg. were recorded in a group of 54 normal subjects of both sexes (age 30.15±9.12 years). P100 latency was measured in all subjects and the data were analyzed in the whole sample and in a selected subgroup of subjects of both sexes with comparable head size. Results In the study group overall, the P100 latency was slightly shorter in females than males and this small difference reached only weak statistical significance ( P<0.04) whereas head size differed significantly between sexes (females<males) ( P<0.001). No difference was found in the P100 latency in the subgroup of the two sexes with a comparable range of head size. Conclusions These findings suggest that VEP latency is relatively constant in a sample of healthy subjects. The slight sex difference in P100 latencies observed in a normal sample is mainly related to the slightly smaller average head size in females than in males. Significance Head size, not sex, should be considered for VEP latency normative studies.