SYNOPSIS Visual evoked potentials (VEP) were recorded and plasma estrogen, progesterone, FSH and LH hormones were determined in a group of patients with menstrual migraine and in healthy controls. Consistent differences from controls were found in the VEPs of migraine patients, justifying the use of VEP recording as a method of investigating the neurophysiology of migraine. The VEPs were not dependent on the hormonal cycle, except for responses to flashes 10/sec which in healthy persons were higher in the luteal phase. This was less clear in migraine patients. Some of the patients showed strong asymmetrical VEP distortion, which was always transient; follow‐up revealed later normalisation. The transient and asymmetrical VEP distortion seemed to relate to the asymmetrical symptoms of migraine, but a direct connection between the two was not established.