Prions are a new concept in medicine and biology. The concepts about α-helix, β-sheet, peptide bond, hydrogen bonds are discussed. Prion diseases cause fatal zoonotic transmissible spongiform encephalopathy, Alzheimer, Huntington and Parkinson diseases in animals and humans. The earliest known Prion disease is Scrapie. Kuru is a fatal neurodegenerative disorder caused by abnormally folded Prion proteins, which leads to symptoms as tremors, loss of coordination. Creutzfeldt–Jakob disease and Gerstmann–Sträussler–Scheinker syndrome are fatal degenerative brain disorders. Fatal familial insomnia results in trouble sleeping. Alzheimer disease causes 60–70% of dementia. Huntington disease is inherited results in the death of brain cells. Prion disease is the transition from α-helix-rich PrPC to rich in β-sheets, responsible for aggregates, and amyloid fibrils. There is no therapeutics to reverse human Prion diseases. Heparin mimetics inhibit Prion propagation in Scrapie infected cells. Other antiprion drugs are tetrapyrroles, branched polyamines, lichens, and β-sheet breaker peptides.