Prion diseases are associated with the accumulation of an abnormal isoformof cellular prion protein (PrP Sc ), which is the principal constituent of prions. Prions replicate in lymphoreticular tissues before neuroinvasion, suggesting that lymphoreticular biopsy samples may allow early diagnosis by detection of PrP Sc . Creutzfeldt-Jakob Disease (CJD) is the most frequent prion disease in humans. Clinical diagnosis of sporadic (CJD) is based on the evaluation of rapidly progressive dementia, ataxia, myoclonus, changes on the electroencephalogram and other neurological signs. We report a problable (CJD) case in Santa Barbara surgical center, Rio de Janeiro, Brazil. From our clinical case, we decided to do a brief review about (CJD) researching at Medline and Pubmed, using terms Creutzfeldt-Jakob disease and Prion diseases. A definite diagnosis, however, is confined to cases that have been evaluated neuropathlogically or by equivalent diagnostic techniques. The range in clinical expression of the disease is better appreciated and the existence of "atypical" cases of CJD is increasingly recognized. The clinical characteristics, laboratory findings, differential diagnosis, mechanisms of transmission and the actual therapeutic approach are discussed.