INTRODUCTIONAcute diarrhea disease is the second cause of death among all infectious diseases in children younger than 5 years of age worldwide. The aim of this study was to employ a combination of biochemical, microbiological and molecular diagnostic techniques to investigate the stools of Iranian children with acute diarrhea for bacterial enteropathogens.METHODDiarrheagenic Escherichia coli, Shigella spp., Salmonella spp., Campylobacter spp. and Yersinia spp., were investigated from June 2003 to June 2005, in 1087 children less than 5 years old with acute diarrhea. Stool specimens from children were studied for enteropathogens both by standard culturing and molecular methods. This study was designed on hospital based.RESULTThe highest incidence values were found in the summer and in children less than 1-year-old (42.7%). The Pathogenic bacteria recovered out from fecal samples of 555 (55.1%) patients had the following profile: Shigella spp. (26.7%) was the most prevalent bacterial pathogen and Shiga-like toxin producing E. coli (STEC) and Enteroaggregative E. coli (EAEC) 105 (18.9%) and 92 (16.6%) had the second and third highest prevalence, respectively. Enteropathogenic E. coli (EPEC), Campylobacter, Salmonella and Enterotoxigenic E. coli (ETEC) were found in 70 (12.6%), 60 (10.8%), 42 (7.6%), and 38 (6.8%) positive samples, respectively. In this study neither Yersinia nor E. coli O157:H7 were found. Of the 30 co-infections detected, Shigella flexneri and Campylobacter jejuni accounted for more than 50%.CONCLUSIONInformation about the prevalence of wide-range Shigella and STEC may facilitate the control and management of infant diarrhea diseases in Iran. The results of this study suggest that comprehensive surveys are needed in different parts of the country in order to identify the incidence of different enteropathogenic diarrhea, especially diarrheagenic E. coli in children in Iran.