The Tolosa-Hunt syndrome (THS) is characterized by remittent and sometimes recurring episodes of painful ophthalmoplegia. The etiopathogenesis is still unclear and is an object of controversy. A non-specific granulomatous process of the wall of the cavernous sinus is claimed by many authors as the possible cause, on the basis of a few pathological studies. Other authors suggest the possible role of autoimmune or specific inflammatory processes localized in the retroorbital perineural tissues. The clinical, laboratory and radiological findings of the eight cases reported in the agreement with those previously described in the literature. However, the visual evoked potentials (VEP) were delayed in three of the four cases in which they had been studied. This finding, together with the observation that some analogies exist between THS and other well known neuritic processes of the cranial nerves, may suggest that at least in some cases THS may be related to an ocular polyneuritis.