Cerebrospinal fluid (CSF) from 115 patients with several neurological disorders were tested for the presence of myelin basic protein (MBP), fragment P1 43-88. Cases were divided into groups according to neurological diagnosis. The control group (50 patients with chronic headache) presented normal CSF composition and presented no evidence of the presence of MBP. MBP was found in: four cases of the 44 of neurocysticercosis; three of the 8 cases of multiple sclerosis; one case of schistosomiasis with spinal cord involvement. Neuroimmunological data are discussed considering results found in this investigation.