A ‘new’ group of pathogenic agents, enterohemorrhagic Escherichia coli (EHEC) (particularly the strains of O157 serogroup), emerged in the last 20 years causing an increased number of sporadic and epidemic diarrhoeal diseases with hemorrhagic enterocolitis as a most common clinical manifestation of the infection. As a consequence of the absorption and cytotoxic effect of the main virulence factor of these bacteria - verotoxin (shiga-toxin), in about 10% of the affected persons extraintestinal complications, most frequently hemolytic-uremic syndrome (HUS), occurred 7-14 days after an episode of diarrhoeal disease. The first case of hemorrhagic enterocolitis with the documented EHEC O157 infection in Yugoslavia is presented in this paper. Considering the existing expansion trend of these carriers, practitioners should be aware of them in case of the occurrence of diarrhoeal disease (particularly hemorrhagic enterocolitis), and keep these patients under control during the reconvalescence period because of potential development of extraintestinal complications, such as HUS.