The Tolosa-Hunt syndrome (THS), a steroid-responsive painful ophthalmoplegia secondary to idiopathic granulomatous inflammation, historically has been categorized as a diagnosis of exclusion because of its nonspecific radiologic presentation. Five patients who satisfied the anatomic and clinical criteria of this syndrome underwent high-resolution CT of the orbital apex/cavernous sinus region. Two patients were diagnosed as having orbital apex pseudotumor, two as having cavernous sinus inflammation, and one as having a cavernous sinus epidermoid by the characteristic CT and clinical findings. Follow-up studies while the patients were asymptomatic demonstrated complete resolution of the CT abnormalities in four patients and clinical improvement in all five patients. Our data suggest that orbital apex pseudotumor and granulomatous inflammation of the cavernous sinus have similar clinical features and should be considered as part of the spectrum of THS. With the advent of high-resolution CT, THS may now be a diagnosis of inclusion. Symptomatic improvement after steroid therapy is an essential but not absolute proof of the syndrome, since lesions such as lymphomas may also respond to steroids. Resolution of the soft-tissue inflammation of CT is an additional criterion for diagnosis.