Creutzfeldt–Jakob disease (CJD) is a rare neurodegenerative disease caused by the prion protein. In the search for biochemical markers for CJD, cerebrospinal fluid (CSF) of 101 patients was analysed for 14-3-3 protein, hTau-protein and amyloid-beta 1-42 (Abeta_1-42). The 14-3-3 test had a specificity of 91.5% and a sensitivity of 84%. The hTau test resulted in 95% specificity and 74% sensitivity, when a cut-off of 1530 pg/ml was used. Abeta_1-42 detection in CSF of 29 probable or definite CJD patients revealed significantly decreased values (p=0.01) compared to a group of 22 neurological controls. In the CJD patients a mean of 319+/-102 pg/ml was found. In the neurological control group a mean of 553+/-268 pg/ml was observed. In patients with a false positive 14-3-3 test (n=5) a mean of 716+/-441 pg/ml was found. We conclude that determination of Abeta_1-42 levels in CSF can be useful for identifying false positive 14-3-3 results in suspected CJD patients. We also compared the presence of senile plaques and the Abeta_1-42 levels in CSF of CJD patients. No clear correlation between them was found in this series. This signifies that the deceased Abeta_1-42 levels in CSF are not just due to plaque retention but that other mechanisms must also play a role.