Shiga-toxin producing Escherichia coli (STEC) is an enteric pathogen that have been linked to outbreaks from foodborne and water borne sources. The present investigation was done to study the distribution of O - serogroups of Shiga-toxin producing Escherichia coli isolated from milk samples collected from different governorates in Egypt. 158 samples were
randomly collected and immediately transferred to laboratory. All samples were cultured and E. coli strains were isolated then identification of O serogroups was done by slide agglutination. The isolated E. coli strains were positive for incidence of 7 serotypes namely O157, O26, O111, O78, O125, O158, and O127. O157 (12.64%) and O26 (9.48%) were the most frequently identified serogroups. High prevalence of O157, O26 strains and other important serogroups which pose an important public health problem regarding the consumption of raw milk was discussed