AIM: To evaluate the retinal vessel diameters in patients with migraine by optical coherence tomography (OCT). METHODS: In this cross-sectional study, 124 eyes of 62 patients with a diagnosis of unilateral migraine during attack-free period and 42 age- and sex-matched control subjects were included. Migraine patients were divided into the 52 migraine attacks per month group and the >= 5 migraine attacks per month group. All subjects underwent complete ophthalmological and neurological examinations before measurements. Retinal vessel diameters and choroidal thickness were examined with the Spectralis OCT. RESULTS: The mean diameters of the arteries in the eyes on the headache side of control group, >= 5 migraine attacks per month and 52 migraine attacks per month group at 480 pm from the optic disk (Raster 3) were 119.54 +/- 46.69, 136.68 +/- 25.93 and 119.34 +/- 31.75 pm respectively with a steady decline to 105.57 +/- 32.15, 118.18 +/- 31.87 and 108.05 +/- 38.77 pm at 1440 pm (Raster 7), the last measurement point, respectively. The retinal artery diameter measurements were significantly increased in >= 5 migraine attacks per month patients at four out of five measured points compared to control group (P= 5 migraine attacks per month patients at all measured points compared to control group (P= 5 migraine attacks per month patients compared to control group.