BACKGROUND Visual Evoked Potential may be a useful method for understanding the pathophysiologic mechanisms involved in the genesis of migraine. In this study, VEP was evaluated as a tool to assess visual function in migraine with aura and without aura. MATERIALS AND METHODS 35 migraine patients (25 without aura and 10 with aura) and equal number of healthy controls were enrolled in the study. Pattern Reversal VEP using a checker board was performed and compared in the three groups. The latency and amplitude of P100, the most consistent and prominent wave of VEP were analysed. VEP parameters in migraine patients were correlated to frequency of attacks and disease duration. Design-Descriptive study. RESULTS Migraine patients with aura showed significantly prolonged VEP P100 latency compared with migraine without aura and control groups. VEP P100 latency showed significant positive correlation with both the duration and frequency of migraine attacks, the latency increasing with increased duration of migraine and more frequent attacks. CONCLUSION There is involvement of the visual system in migraine with aura rather than migraine without aura. VEP could be regarded as a useful and reliable technique for assessment of the visual dysfunction in migraine, manifesting predominantly by prolongation of P100 latency.