A clinical diagnosis of Creutzfeldt-Jakob disease (CJD) can be established readily in typical cases but not in atypical cases. To investigate the accuracy of clinical diagnosis of CJD, such diagnoses were evaluated retrospectively in autopsy cases. Sixty cases were clinically diagnosed as cases of CJD, of which seven were excluded on the basis of pathologic analysis. These seven misdiagnosed patients showed progressive dementia or disturbed consciousness. Myoclonus and periodic sharp-wave complexes (PSWCs) similar to those of CJD were noted in five and four of the seven patients, respectively. Fifty-six cases were pathologically confirmed as cases of CJD, and three of these were not diagnosed clinically as cases of CJD. Myoclonus was noted in 53 of the 56 pathologically confirmed cases, and PSWCs were noted in 49 cases. According to the difficulties that occur in atypical CJD cases lacking typical clinical findings, the importance of pathologic examination was emphasized. Further information from clinicopathologically investigated cases, particularly atypical cases, will aid in the definitive clinical diagnosis of CJD.