['Prognostication of brain damage after cardiac arrest mainly relies on clinical observations. Recently, it has been shown that biochemical markers of brain damage measured in serum aid in this process. In the present study, we wanted to test the usefulness of CSF determinations of a neuronal protein, the neurofilament protein (NFL).', 'Lumbar punctures were performed during week 2 or 3 in 22 patients surviving cardiac arrests. CSF NFL concentrations were analysed using an ELISA. Levels were increased in cardiac arrest patients. Patients with poor outcome according to the Glasgow outcome scale (GOS), low performance at a mini mental state examination (MMSE) and dependent according to Katz at 1 year follow up had the highest NFL levels. The NFL levels correlated well with anoxia time and coma depth. High positive and negative predictive values, particularly for poor outcome according to GOS were observed.'] Is cSF levels of neurofilament a valuable predictor of long-term outcome after cardiac arrest?