Twenty Salmonella Infantis strains resistant against kanamycin, tetracycline, neomycin, spectinomycin, sulphonamide, nalidixic acid and trimethoprim were selected for this study out of 103 Salmonella strains isolated from broiler samples collected from several markets in the Bolu and Ankara regions of Turkey. The resistance genes aadA1, aphA1, sul1, tet(A), dfrA5/dfrA14 and gyrA were determined for these multidrug-resistant S. Infantis strains. S. Infantis strains contained a mega plasmid with the molecular size of 206 kb. The strains were divided into three groups according to the pulsed field gel electrophoresis patterns of XbaI digested chromosomal DNA. A Ser83→Tyr83 point mutation was found in the gyrA gene of all quinolone-resistant isolates. Filter mating experiments showed that 206 kb plasmid transferred nalidixic acid resistance associated with class I integrons.