A total of 22 Avian pathogenic multi-drug resistant E.coli strains isolated from broiler chickens suffering from colibacillosis obtained from Poultry diseases Department, Animal Health Research institute, Dokki, Giza. E. coli strains were subjected to molecular characterization of some virulence genes (iroN, ompT, hlyF, iss and iutA) by using the Polymerase Chain
Reaction (PCR), the results revealed that all these genes were detected in both chromosomal DNA (77.27%) and plasmid (59.09%) of the examined multidrug-resistant E. coli strains. iroN was detected in (45.45% and 36.36%), ompT in (50% and 36.36%), hlyf in (54.55% and 54.55%), iss in (63.64% and 54.55%) and iutA in (36.36% and 36.36%) in chromosomal
DNA and plasmid respectively.It was concluded that,the misuse of antimicrobials without veterinary supervision and consultation may lead to selection of multidrug resistant E. coli. There is a relationship between the presence of MDR E. coli and the virulence genes which lead to increased virulence and fail of treatment of pathogenic E.coli which in turn increase
the economic losses among broiler chickens.