The 14-3-3 assay in the CSF has a high predictive value for the diagnosis of sporadic Creutzfeldt-Jakob disease (CJD). Our objective was to analyse the trends in mortality and incidence rates of CJD in Catalonia, an autonomous community of Spain, setting the cut off point the date when the 14-3-3 assay was incorporated to our CJD surveillance system. Only definite and probable cases according to the criteria adapted from Masters and colleagues were included for the analysis. Familial cases were excluded after genetic analysis of the PrP gen. We found a quasi threefold increase in the incidence and mortality rates for CJD after introduction of the 14-3-3 assay in our surveillance system in 1997 as compared with the period 1993-1996. Our findings suggest an improvement of case ascertainment in part due to the introduction of the 14-3-3 assay in the surveillance system.