Neuron-specific enolase (NSE) is a dimeric cytoplasmic enzyme detected in high levels in neurons and acts in the glycolytic pathway. It is known that there is a quantitative relationship between the concentration of serum NSE and the degree of cell damage in the central nervous system. We examined serum levels of NSE by enzyme immunoassay in 89 patients with head injury and aimed to evaluate its relationship with neurological status and prognosis of the patients.