Methanogenic archaea are phylogenetically diverse, ancient and environmentally widespread. They are common inhabitants of the gastrointestinal tract of humans and other animals, and produce methane, a potent green-house gas, as a metabolic by-product. Despite the ecological importance and diversity of methanogens, their viruses are virtually unknown. The aim of the VIRMET project is to perform a comprehensive characterization of the virome associated with methanogens using state-of-the-art computational and experimental approaches. We will use a targeted strategy to identify and compare methanogenic virus genomes by using publicly available and in-house faecal viromes and metagenomes. In parallel, we will isolate viruses infecting the main human-associated methanogens and characterize their effect on host growth and physiology. This innovative and pioneering project should answer fundamental questions about the diversity, evolution and impact of the methanoarchaeal virome.