In order to evaluate information on acute stroke through the study of cerebrospinal fluid (CSF) data em 1500 patients were analysed in the first 48 hours following stroke. Cases were distributed in three groups according to CSF basic findings: type 1, CSF without erythrocytes and without xanthochromy; type 2, CSF without erythrocytes and with xanthochromy; tipe 3, CSF with erythrocytes and with xanthocromy. Data on each type are discussed as well as correlation findings. Systemic metabolic disturbances, blood-brain barrier impairment and central nervous system lesions are discussed as to the role they have in CSF changes observed in stroke. Indication of CSF exam in stroke is reviewed taking into account progress in neuroimaging techniques.