During a 16-month study period at a children's hospital, 32 children developed nosocomial gastroenteritis caused by astroviruses. Twenty-five of these occurred during 2 epidemic outbreaks in medical and surgical infants' wards. From the community, 13 confirmed cases were admitted during the study period. Both community-acquired and nosocomial cases occurred during autumn, winter and early spring. The atack rates during outbreaks ranged between 7 and 62% and were highest among children with underlying gastrointestinal diseases. Diarrhea and vomiting were the most common clinical manifestations. The median duration of symptoms was 4 days and that of virus excretion was 5 days. Hospital infection with astroviruses is common and usually affects children less than 2 years of age. The probable mode of transmission is spread via contaminated hands.