A rapidly progressing dementia, followed by focal neurological signs and evidence of periodic sharp waves complexes in the EEG may lead to the clinical suspicion of Creutzfeldt-Jakob disease (CJD). Nevertheless the cases of CJD are diagnosed seldom. Patient, a 66-year-old man was admitted to Department of Neurology with progressive disturbances of communication. There was no family history of similar diseases. In the neurological examination aphasia, behavioural abnormalities and grow of muscles tension was found. There were also periodic abnormalities in EEG. The rapidly progressive worsening of consciousness persuaded us to recognizing CJD. We diagnosed him as having CJD as we detected the 14-3-3 neuronal protein in cerebrospinal fluid. Cranial MRI showed mild cerebral atrophy with periventricular white matter hyperintensity in T2-weighted scans. During the observation the contact with patient rapidly worsened and he died after two weeks hospitalisation. The CJD was proven by the typical EEG, neuronal protein in CSF and by autopsy too. This is the one of few cases diagnosed alive.