One hundred and fourty eight children with diarrhea of less than 1 week duration, admitted to hospital, were studied. Sixteen cases with enterotoxigenic Escherichia coli (ETEC) associated diarrhea and 132 cases from whom ETEC was not isolated were compared. Age, nutritional status and duration of illness were similar in both groups. Children with ETEC infections passed more loose stools (P = 0.006), were more severely dehydrated (P = 0.0007) and were more lethargic (P = 0.04) on admission than children without ETEC infections. Complications were more often observed in the ETEC group. Six children with ETEC infections had severe hypotension and required intravenous rehydration therapy (P = 0.005). Four of them developed hypovolaemic shock (P = 0.002). Multiple antibiotic resistance was observed in 75% of ETEC isolated from children with diarrhea. Seasonal variation of ETEC shows a bimodal distribution before and after the rainy season. Concomitant infections were diagnosed in 71% of children, 66% got antibiotic treatment and 93% received oral rehydration solution (ORS). Two children died during hospitalization. Case fatality rate was 1.35 per cent. The findings of this study indicate that ETEC is a common cause of diarrhea in Khmer children and can cause severe disease.