A PCR method was developed for the simultaneous detection of Escherichia coli O157 and H7 antigens. Two PCR primer pairs for amplification of both E. coli O157 rfbE and H7 fliC genes, which are necessary for the expression of the O157 and H7 antigen respectively, were performed for the detection of E. coli O157: H7. All Shiga toxin-producing E. coli (STEC) O157: H7 and STEC O157: NM strains were positive for both E. coli O157 rfbE and H7 fliC genes. Non-STEC O157 strains were positive only for E. coli O157 rfbE genes and H7 strains except O157 were positive only for H7 fliC genes . Some of the nonmotile strains were positive for H7 fliC genes. No cross-reaction was observed with other E. coli serotypes (except O157 and H7) and other bacterial species, like Salmonella O30 and Citrobacter freundii which react with E. coli O157 antiserum. It is recommended that PCR amplification of both E. coli O157 rfbE and H7 fliC genes is one of the most specific methods for E. coli O157: H7 identification.