Creutzfeldt-Jakob disease (CJD) is a rare neurodegenerative human disorder with an incidence of one case per 1000000 per year. Recently new diagnostic tests such as neuron-specific enolase (NSE), S-100, tau-protein and protein 14-3-3 have been established as markers in prion diseases. NSE is elevated in case of rapid nerve cell loss so quantitative measurement of NSE in cerebrospinal fluid (CSF) might correlate with the disease progression. To further evaluate this hypothesis we analysed longitudinal CSF samples from 16 CJD patients. The first spinal tap was taken two weeks after the first clinical signs of a neurodegenerative disorder. This showed an elevation of NSE which continued during the course of the disease. Longitudinal examination of neuron-specific enolase in cerebrospinal fluid therefore may be useful for differentiation between CJD and other dementias.