A short history of prion diseases is given. Scrapie as disease of sheep was first seen in 1732. In the last century, similar diseases were described in goats, minks and other animals. In the beginning of the last century, the first cases of Creutzfeld Jakob Disease (CJD) were described. This neurological disease of humans develops in about 100 cases in Germany per year and leads to death within about 6 months. All these diseases show spongiform degenerations of the brain (spongiform encephalopathy) and are transmissible, even iatrogenic. Similar cases were seen in the 50’s of the last century in Papua New Guinea in the Fore tribe resulting from cannibalism. In 1986, “mad cow” disease was described in the UK: it was later called Bovine Spongiform Encephalopathy (BSE). About 10 years later, a variant of CJD (vCJD) was seen in humans and this is attributed to the consumption of infected meat. All these diseases are caused by a so-called prion protein. The individual risk of getting vCJD seems to depend on a genetic polymorphism in the prion protein gene. The EU has taken several steps to prevent the spread of the disease in humans and animals, e.g. testing cattle, culling and burning of infected cattle and cohort animals and eliminating risk materials (like brain tissue). These schemes have been costly and have changed consumer behaviour. In the healthcare sector, recommendations were published to limit the spread of the disease by instruments used in unknown prion carriers. Unfortunately, these steps are not safe in any case and are very expensive. The real extent of the risk posed by prion diseases remains an open question.