Rotaviruses and adenoviruses are the main aetiologic pathogens of gastroenteritis in infants. Adults may also be concerned with usually mild clinical symptoms. An epidemic of viral gastroenteritis occurred in a long-term hospitalization ward from July 25 to August 21, 1991: 101 patients. This study involved 26 females and 6 males with a mean age of 86 years (range 70-101 years), presenting clinical symptoms of gastroenteritis. The clinical attack rate was 27.7%. Outcome was favourable for the majority of patients who recovered in 4-5 days. The main clinical signs were diarrhoea (90.6%), hyperthermia (18.8%) and vomiting (18.8%). Virology investigations gave the diagnosis of 8 rotavirus infections, 6 adenovirus infections and 2 rotavirus and adenovirus mixed infections. Among staff members, 3 rotavirus and one adenovirus infections were diagnosed. The precise origin of the epidemic could not be determined from rotavirus electropherotypes obtained from stools of elderly and paediatric patients hospitalized during the same period. This outbreak recalls the viral involvement in diarrhoeal episodes of elderly people. These episodes of viral gastroenteritis are responsible for high morbidity in the elderly and may upset a precarious physiological state.