During a period of 15 months 621 hospitalized children with acute gastroenteritis and 152 control children were investigated for etiologic agents of the disease. Putative enteropathogens were identified in 86% of the patients and 10% of the controls. Common viral agents associated with gastroenteritis among children included rotaviruses (45%) and enteric adenoviruses (4%). Bacterial pathogens infecting children were Salmonella serotypes (24%), enterotoxigenic Escherichia coli (9%), Campylobacter jejuni (7%), enteropathogenic E. coli (7%), Shigella (4%) and enterotoxigenic Aeromonas sp. (1%). The highest incidence of infections was observed in the 3- to 25-month age group. Mixed infections were observed in 12% of the patients. Viral gastroenteritis was clinically mild and of short duration. Upper respiratory tract infections, vomiting and watery stools were common features. In contrast bacterial gastroenteritis was more severe; stools were frequently bloody and abdominal pain, cramps, shock, convulsions and milk intolerance were predominant clinical features. Comparative analysis revealed differential features of bacterial and viral gastroenteritis which should help clinicians to make a tentative diagnosis and to start treatment early.