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Transmissible spongiform encephalopathies (TSEs) are a group of progressively degenerative diseases, caused by prions, that affect nervous system of animals and humans and appear always with fatal outcome. The accumulation of prions in the nervous tissue causes neuronal death and degenerative lesions visible with microscope as spongiosis. The disorders affect the brain function, including severe neurological symptoms that become worse chronically. The origin of infectious prions may be genetic, sporadic, iatrogenic or via ingestion of infected food and feed. The main TSEs that affect animals are scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle and chronic wasting disease in deer (CWD). In the 1980s and 1990s, bovine spongiform encephalopathy appeared in cattle as an outbreak. The epidemiological survey revealed that the source of the prions was the meat and bone marrow (MBM) from diseased ruminant used as supplement in the feed. The entrance of these infected cattle in the food chain has caused an outbreak of a variant form of CJD. The strict measures put in place including the feeding ban contributed to the dramatic decline of BSE and vCJD cases. In 2001 the first case of BSE was reported in Greece and since then, a strict active surveillance program was applied concerning all the bovine categories. Scrapie is a prion disease affecting sheep and goats. Scrapie is known at least from 1732 and exist almost all over the world. The disease also cause severe neurological symptoms (excessive lip smacking and convulsive collapse). Even though scrapie does not considered as zoonosis, strict measures in affected flocks are imposed by the EU legislation. Despite the active surveillance program the scrapie cases in Greece are in the highest rate among the Member States