A 33-year-old woman with a long history of typical migraine without aura developed a pupillary-involving right third nerve palsy, after a typical migraine attack. The right pupil was 5 mm and showed delayed direct and consensual photomotor responses; the left pupil was 3 mm and reactive. Pupillary reaction to convergence was slow on the right eye. Ptosis, impaired elevation of the eye and weakened adduction were noted in the right eye. CT scan of the brain showed no abnormalities, whereas a CT digital cerebral angiography revealed a fetal-type right posterior cerebral artery (PCA). MRI disclosed thickening and contrast-enhancement of the cisternal portion of the right oculomotor nerve. A lumbar puncture, performed 5 days after the onset of ocular symptoms, yielded acellular cerebrospinal fluid (CSF) with normal protein and glucose levels. Ptosis and diplopia recovered within a week, whereas blurred vision, anisocoria and accommodation deficit subsided after 10 weeks.