We assessed the prevalence of Wernicke encephalopathy (WE) in all 657 cases suspected of Creutzfeldt-Jakob (CJD) referred from 2001 to 2006 to the French Neuropathology Network of CJD. Clinical, biological and imaging data were reviewed when the diagnosis of WE was made at autopsy. No CJD was found in five cases suspected of sporadic CJD. In these five cases, myoclonus had been observed in four, CSF 14-3-3 protein in two. In 14 other cases, WE was combined with CJD, 13 of which were sporadic. These belonged mainly to the molecular variants of sporadic CJD associated with a long duration of disease. This stresses the necessity of remaining alert to the diagnosis of WE when CJD is suspected.