Hypertrophic pachymeningits is an unusual cause of neurological symptoms and is often secondary to infections, carcinomatosis or inflammatory diseases. it may also be idiopathic. We report a case of pachymeningitis which was manifested primarily by psychosis and visual loss with optic atrophy and destruction of nasal septum. The patient, a 45 year old woman was submitted to extensive investigation without evidence of any underlying disease. A meningeal biopsy was performed and showed a mostly unspecific inflammatory process with extensive fibrosis of the dura and few early stage granulomas. These findings suggest either neurosarcoidosis or idiopathic hypertrophic pachymeningitis.611107111