Escherichia coli O157:H7 is now recognised as an important human pathogen. Illness caused by E. coli O157:H7 infection can range from self limited, watery diarrhea to life-threatening manifestations such as hemorrhagic colitis, hemolytic uremic syndrome or thrombotic thrombocytopenic purpura. The mode of transmission is primarily through food (e.g. undercooked minced beef products, especially beef burgers, raw cows' milk and cheese, contaminated pasteurised milk and untreated water.). Studies to date indicate that cattle is an important reservoir of the organism. Public health measures to control VTEC infection are broadly similar to the measures needed to control other gastro-intestinal infections. Because of the potential low infection dose, laboratory diagnosis of O157 VTEC in food samples has developed over recent years with the use of liquid enrichment and the development of methods such as immunomagnetic separation. VTEC of other serogroups than O157 have no reliable biochemical, serological or morphological characteristics (other than VT production itself) to distinguish them from commensal E. coli. Thus to detect VTEC other than O157 and phenotypic variants of E. coli O157 in food, we have to use methods for detection of verocytotoxin production and VT genes.