To determine the role of enteric pathogens in acute childhood diarrhoea in Hong Kong, 388 children with diarrhoea and 306 children of similar age without diarrhoea were evaluated in a hospital-based study during a one-year period from August I 994 to J u l y I 995. Of the diarrhoea1 cases, 5 5 % were under T year and 9 5 % were below 5 years of age. On admission, 22% had some dehydration but none was severely dehydrated. All children were well nourished. Over 60% of children with diarrhoea had one or more pathogens in their stool. Rotavirus was the most commonly isolated pathogen (34.6'Yn), followed by Salmonella (23.3%), Campylobacter (4.7%) and Shigella (2.1%). Rotavirus was not assessed in the controls and was detected mainly during the winter months December t o February. Bacterial pathogens were identified more commonly in diarrhoea patients ( 3 0 % ) than in controls (5.6%) (Pio.oor). Despite rapid recent socioeconomic development i n Hong Kong, non-typhoidal Salmonella diarrhoea remains a significant local problem in infants under T year. Further detailed assessment of the transmission and prevention of this infection i s required.