In order to evaluate the effects due to acute cerebrovascular disease on serum and cerebrospinal fluid (CSF) parameters, biochemical data from 312 patients were studied. In serum, CK, LD and alpha 1 protein fraction showed a moderately close relationship to the severity of stroke. In CSF there could not be observed any relation between enzymatic activities (LD, ASAT, CK) and the severity of the disease. The same result was found for CSF protein and the ratio CSF albumin/serum albumin, parameters which are indicative for Blood Brain Barrier (BBB) disturbances. Substances from the intermediate metabolism in the Central Nervous System (CNS) (lactate and pyruvate) were evidently raised in CSF and there was a clear relation between the CSF concentration and the severity of stroke. No indication for IgG immunoglobulin abnormalities in CSF was found. The concentration of neurotransmitter metabolite 5HIAA in CSF was significantly higher in (in)completed stroke than in Transient Ischaemic Attack.