Verotoxin-producing Escherichia coli strains have been associated with acute hemorrhagic colitis since 1982. We have systematically investigated this pathogen in our laboratory, in all stool samples submitted for culture during a fourteen month period, by using MacConkey sorbitol agar to isolate non sorbitol fermenting Escherichia coli strains. Coated latex particles with an antiserum against Escherichia coli O157 were used to detect O157 serogroup Escherichia coli. A completed serological study and verotoxin assay was performed in all positive strains. We have found two non-related cases of verotoxigenic Escherichia coli infection in two children. In one case, the main clinical picture was an acute hemorrhagic colitis and the other one was a diarrhea without presence of blood, with fever and vomiting. Both cases improved without antimicrobial treatment. No systemic complications appeared in any of the cases during the infection. The infection incidence was 0.07% of all positive stool cultures. The few documented cases of this infection in our country should encourage to investigate this pathogen in order to know its real incidence in our environment.