Forty-five isolates from root nodules of chickpea (Cicer arietinumL.) growing in the western and northwestern regions of Iran were characterized by phenotypic properties, repetitive element sequence-based (rep)-PCR, and 16S rRNA sequences. Based on phenotypic features, the isolates could be divided into three main groups at 92 % similarity. Nodulating isolates of those grouped in clusters II and III were grouped with reference strains ofMesorhizobium mediterraneumand M. ciceri, respectively. The three isolates of cluster I did not induce nodules on the host plant. Based on the analysis of the fingerprint patterns generated by enterobacterial repetitive intergenic consensus- and BOX-PCR, the strains were classi-fied into six clusters (A–F) at the 75 % similarity level. These six clusters could be further divided into several subgroups at the 85 % similarity level. The phylogenetic analysis based on 16S rRNAgene sequences showed that representative isolates were closely related toM. mediterraneum, M. ciceri,and Agrobacterium tumefaciens
