The human prion diseases have traditionally been classified into Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler syndrome (GSS) and kuru. The clinically defined categories: CJD, GSS, and kuru may be divided further into three etiological categories: sporadic, acquired, and inherited. The coding sequences of mammalian prion protein genes are highly conserved in a similar way to other structural proteins, presumably by deleterious selection of coding mutations. Symptomatic treatment of various neurological and psychiatric features can be provided and a range of supportive services are likely to be required in the later stages of the disease. A number of approaches to rational therapeutics are being studied in experimental models. Anti-PrP antibodies have been shown to block progression of peripheral prion propagation in mouse models, and humanized versions of these antibodies could, in principle, be developed and used for both post-exposure prophylaxis and during established clinical disease.