MAO A enzyme, a form of MAO, plays a critical role in the regulation of catecholamines and indolamines (especially in norepinephrine and serotonin) neurotransmission. There are a number of studies in brain electrophysiology literature searching for relations between evoked potentials and platelet MAO activity and/or several psychiatric traits mentioned to be affected by MAO. A variable number of tandem repeats (VNTR) polymorphism was found in the promoter region of this gene associated with MAO A transcriptional activity. In our study, we investigated the effects of MAO A gene polymorphism on N1 component of event-related potentials obtained by auditory oddball and auditory novelty paradigms. Allele 1 and allele 3 were common alleles for this gene in our population (%98). The amplitude and latency differences of N100 wave between these allelic groups were analyzed by an ANOVA design with the between subject factor, genotype, and within-subject factor, topographic distribution. There were significant overall differences between the two allelic groups in N100 latency, which reached a statistically significant level in N100 potentials evoked by the target stimuli of the oddball and the standard stimuli of the novelty paradigm (p=0.035 and p=0.01, respectively). The N100 latencies of allele 3 group were longer than those of allele 1 group. Because of the high serotonergic innervation of the primary auditory cortex, MAO A gene could affect N100 potential via serotonin level regulation. These results suggests that MAO A gene could be a neurobiological substrate for the interindividual variance of auditory N100 potential in several conditions.