Astroviruses have been shown to be important aetiological agents associated with gastroenteritis in children, as have rotaviruses and the enteric adenoviruses. However, no inclusive studies have been conducted in South Africa to allow a comparison of the relative roles of these different viral agents. In this study, stool specimens were obtained between 1991 and 1993 from 225 young children with acute gastro-enteritis. These were examined for the presence of astroviruses using a monoclonal antibody-based ELISA, and for rotaviruses and enteric adenoviruses using commercially available kits. A control group of 56 infants and young children without symptoms of diarrhoeal illness was included in the study. Astroviruses were detected in 7% of the stools compared with 20% infected with rotaviruses and only 3% infected with enteric adenoviruses. In the control group, one specimen each had astrovirus or adenovirus and two shed rotaviruses. The astrovirus prevalence observed in this study is similar to that reported in other developing communities. Rotavirus and astrovirus infections were more prevalent in the autumn and early winter than in other seasons. Astrovirus and rotavirus infections predominated in children between 3 and 22 months of age.