Numerous viruses found in the gut are not associated with primary infection or disease of the gastrointestinal tract. Other groups or viruses are not classically associated with infection of the gut but can infect the gastrointestinal tract in immunocompromised individuals (herpes simplex virus, cytomegalovirus, papillomavirus ....). The viruses associated with gastroenteritis represent a large number of taxonomic group. Because these viruses have in general been difficult to cultivate, most members of this group were firstly detected by electron microscopic examination (adenovirus, astrovirus, calicivirus, coronavirus, rotavirus ....). The most widely used diagnostic techniques for adenovirus (40/41), rotavirus and astrovirus detection in faecal samples include immunoassays such as Elisa and latex agglutination. Nucleic acid hybridization techniques have generally not proven to be substantially sensitive and the more sensitive techniques recently developed use the polymerase chain reaction (adenovirus) or the reverse transcription/polymerase chain reaction (astrovirus, calicivirus, coronavirus, rotavirus). Special efforts have been made in the search for efficient procedures to extract viral nucleic acids, and to establish the optimal conditions for the amplification and identification of PCR products but the candidate viruses were very different, consensus procedures were not determined, and amplification kits were not actually commercialized.