The prognostic value of cerebrospinal fluid (CSF) and serum neuron-specific enolase and brain-type creatine kinase isozyme (CK-BB) measurements was studied in 75 consecutive victims of out-of-hospital cardiac arrest. All patients with a CSF neuron-specific enolase level of more than 24 ng/mL 24 hours after cardiac arrest remained unconscious and died. The CSF CK-BB level was as reliable as an index of brain injury. Cerebrospinal fluid neuron-specific enolase, CSF CK-BB and serum neuron-specific enolase levels correlated with the neurological outcome at 3 months. Thus, the analysis of these enzymes in CSF seems to be useful in the early prognostic assessment of cardiac arrest victims.