This chapter reviews the role of bacteriophages in neurodegenerative diseases, with a focus on how phages contribute to the genesis, progression, and maintenance of neurodegenerative diseases. The existing research on the role of human pathogen phages is very limited, with even less data on their connection to neurodegenerative pathologies. The pathogenic mechanisms of the microbial presence in the cerebrospinal fluid and brain in neurodegenerative pathogenesis are multifaceted and include the development of an autoimmune cascade and an altered inflammatory response. Protein misfolding, which triggers the formation of neurotoxic aggregates, has become the leading theory for the recognition of Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis, and other neurodegenerative pathologies as prion-mediated disorders. Neurodegenerative pathologies, and Alzheimer’s, in particular, are known to be associated with alterations in gut microbiota that influence central nervous system function through the gut-brain axis. The role of microbiota in the development and progression of neurodegeneration is most studied in Alzheimer’s.