Eighteen patients with neurobrucellosis are described. Eleven patients had meningitis alone or with papilledema, optic neuropathy, or radiculopathy. Four patients had meningovascular complications manifested by stroke or intracerebral hemorrhage from a presumed mycotic aneurysm. Two patients had parenchymatous dysfunction, including a child who had a cerebellar syndrome without evidence of direct infection of the central nervous system. One patient presented with polyradiculopathy. Twelve of 16 patients had pleocytosis; none had cell counts greater than 419 x 10(6)/L. Most patients had hypoglycorrhachia and elevated levels of protein in the cerebrospinal fluid (CSF). Results of an agglutination test for Brucella in serum were positive for all patients. Six of 16 patients had positive blood cultures, and four of 14 had positive CSF cultures. Antimicrobial treatment included concurrent administration of two or more of the following drugs: streptomycin, tetracycline (or doxycycline), rifampin, and trimethoprim-sulfamethoxazole. Eleven patients fully recovered. Five patients were left with residual neurological deficits. Four of these patients suffered permanent hearing loss, one of whom also had significant loss of vision in one eye. One elderly senile patient with meningovascular brucellosis remained in a vegetative state despite receiving antimicrobial therapy for 6 months. One patient died due to rupture of a mycotic aneurysm within 7 days of initiation of therapy. One other patient was treated after sustaining an intracerebral hemorrhage, but this patient's condition was diagnosed only after discharge.