In a 1 year study of diarrhoea in a village in rural Bangladesh, enterotoxigenic Escherichia coli (ETEC) were the most frequently detected enteropathogens; shigellae were the second most commonly detected enteropathogens and rotaviruses the third. ETEC and rotavirus were found in 31% of diarrhoea episodes experienced by children aged less than 2 years and in 70% of episodes associated with dehydration. Furthermore these two pathogens were identified in the stools of 77% of young children with life-threatening dehydration seen at a diarrhoea treatment centre. The association of ETEC and rotavirus with such a substantial proportion of cases of dehydrating diarrhoea suggests that immunoprophylaxis to reduce the high incidence of deaths from diarrhoea in developing countries may be feasible and that vaccine development should concentrate on these two enteropathogens.