Avian colibacillosis (AC) is frequently reported from poultry farms in the west of Iran. The aim of the present survey was to evaluate the phylogeny of Escherichia coli isolated from AC through the Clermont triplex protocol and gyrA gene sequencing. One hundred and fifty fresh carcasses suspected of having died from colibacillosis were sampled. The specimens were examined for E. coli isolation and identification. The extracted DNA repertoire of the isolates was subjected to phylogenetic analysis using Clermont triplex PCR. A DNA fragment of 1.8 kbp of the gyrA gene was amplified from a representative of each phylogroup or subgroup and the final product was sequenced to depict a phylogenetic tree. In general, among 119 E. coli isolates, 31.93%, 6.72%, 34.45%, and 23.52% were clustered in phylogroups A, B1, B2, and D, respectively. The phylogenetic assignment of the isolates based on the phylogenetic tree was completely uniform with the results of the triplex method. The outcome represents the segregation of avian pathogenic E. coli isolates to various phylogroups in the region. Moreover, the precise cluster analysis of E. coli based on gyrA sequencing confirms this method as a robust candidate for phylotyping of the bacterium. [ABSTRACT FROM AUTHOR]