This pilot study investigated the effect of menstrual cycle phase (late luteal and mid-follicular) on cerebral perfusion changes during photic stimulation in both controls ( n = 5) and true menstrual migraine patients ( n = 5). No significant differences in resting baseline perfusion were observed between the two groups during either phase of the menstrual cycle. During the late luteal phase, changes in perfusion within the occipital lobe due to photic stimulation were similar for both groups. However, during the mid-follicular phase, occipital perfusion during visual stimulation decreased for controls but significantly increased for true menstrual migraine patients ( P < 0.05). A two way repeated measures ANOVA also demonstrated a significant difference between menstrual migraine patients and controls for photic activation ( P < 0.05).