Prion diseases (or transmissible spongiform encephalopathies) are rare, infectious neurodegenerative disorders caused by the accumulation of aberrant prion proteins in the brain. TSEs can affect both animals and humans and can be transmitted with varying degrees of efficiency between species. Prion disease can be sporadic, genetic, or acquired. Testing in humans is not feasible, yet, alarmingly, vCJD has been shown to transmit through blood transfusions. Other patients have been iatrogenically infected from surgical instruments that were contaminated with prions. Prions are extremely difficult to inactivate and standard disinfection methods for surgical equipment are inadequate. There are at present time no effective treatments for TSEs in humans or in animals. The incubation time is generally long, but death usually occurs within months after the onset of clinical disease. The aim of this paper is to present an overview of the prion diseases, including medical, historical, legal, and economical perspectives.