The following work informs of the results of isolation, frequency and distribution of enteropathogens in children under five years old, without previous antibiotic treatment, less than seven days with diarrhoea, ambulatory or in Hospital "Dr. Ramón Madariaga" de Posadas, Misiones, República Argentina, from June 1986 to May 1989. From a total of 972 children with diarrhoea, 78% required to be hospitalized. The greatest number of cases were found during spring and summer in children from 1 to 11 months of age. Distribution of the main enteropathogens was: enteropathogenic Escherichia coli (EPEC) (29.4%), parasites (22%), Shigella (16.3%), enterotoxigenic Escherichia coli (ETEC) (14%) and rotavirus (12.9%). Highest incidence of rotavirus was registered in the coldest months and Shigella, ETEC, Salmonella and parasites in the warm months. The group of most affected children were from 1 to 11 months of age, with higher incidence of EPEC, Salmonella and rotavirus, and parasites were found in older children. ETEC and Shigella had no relationship with the age of children. The most frequent association was EPEC with rotavirus. This is the first finding of Salmonella zaiman in humans and of Salmonella hadar in Argentina. Cryptosporidium, etiological agent of serious diarrhoea in the immunocompetent, was isolated in 3.9% of our cases.