Creutzfeldt-Jakob disease (CJD) is a rare dementing illness that usually affects older adults and is characterized by a rapidly progressive dementia, ataxia, and myoclonus. The disease is due to an unusual transmissible protein called a prion. The diagnosis is often suspected on the basis of electroencephalographic (EEG) and clinical findings. Our case was 62-year-old woman, who presented acute onset rapid progressive dementia, myoclonus, heightened startle reaction, extrapyramidal symptoms, and died about 2.5 months after onset of disease. We diagnosed this case as CJD with typical EEG pattern and clinical features.