Antimicrobial resistance in bacteria from the family Enterobacteriaceae is an important indicator of the emergence of resistant bacterial strains in the community. This study investigated the antimicrobial susceptibility of commensal Enterobacteriaceae from free-range chickens to antimicrobial agents using the broth microdilution. In all, 184 isolates (including 104 Escherichia coli, 44 Klebsiella spp, 20 Salmonella spp. and 16 Enterobacter aerogenes) were resistant to ampicillin (89.7%), chloramphenicol (73.9%), ciprofloxacin (33.2%), enrofloxacin (60.3%), neomycin (70.7%), norfloxacin (45.7%), streptomycin (78.8%) and tetracycline (73.4%). Escherichia coli was resistant to ampicillin (92.3%), chloramphenicol (73.1%), ciprofloxacin (34.6%), enrofloxacin (61.5%), neomycin (76.9%), norfloxacin (46.2%), streptomycin (80.8%) and tetracycline (76.9%). The rate of resistance in Klebsiella spp. was ampicillin (90.9%), chloramphenicol (72.7%), ciprofloxacin (54.5%), enrofloxacin (90.9%), neomycin (63.6%), norfloxacin (63.6%), streptomycin (81.8%) and tetracycline (81.8%). Salmonella spp. showed resistance to ampicillin (80.0%), chloramphenicol (80.0%), enrofloxacin (20.0%), neomycin (80.0%), norfloxacin (20.0%), streptomycin (80.0%) and tetracycline (35.0%) but were completely susceptible to ciprofloxacin. Enterobacter aerogenes was resistant to ampicillin (81.3%), chloramphenicol (75.0%), ciprofloxacin (6.3%), enrofloxacin (18.8%), neomycin (37.5%), norfloxacin (25.0%), streptomycin (56.3%) and tetracycline (75.0%). Overall, 147 (79.9%) out of 184 isolates demonstrated multidrug resistance to at least three unrelated antimicrobial agents. The high rate of antimicrobial resistance in bacterial isolates from free-range birds may have major implications for human and animal health with adverse economic implications. Key words: multidrugresistance, commensal Enterobacteriaceae, free-range chickens Otpornost bakterija porodice Enterobacteriaceae na antimikrobne lijekove vazan je pokazatelj pojave otpornih sojeva u populaciji. U ovom je radu mikrodilucijskim postupkom bila istrazena osjetljivost na antimikrobne lijekove bakterija porodice Enterobacteriaceae izdvojenih iz pilica u slobodnom sustavu drzanja. Od 184 izolata (104 izolata bakterije Escherichia coli, 44 Klebsiella spp., 20 Salmonella spp. i 16 Enterobacter aerogenes) na ampicilin je bilo otporno 89,7% izolata, na klormafenikol 73,9%, ciprofloksacin 33,2%, enrofloksacin 60,3%, neomicin 70,7%, norfloksacin 45,7%, streptomicin 78,8% i tetraciklin 73,4%. Izolati bakterije Escherichia coli bili su otporni na ampicilin (92,3%), kloramfenikol (73,1%), ciprofloksacin (34,6%), enrofloksacin (61,5%), neomicin (76,9%), norfloksacin (46,2%), streptomicin (80,8%) i tetraciklin (76,9%). Stopa otpornosti bakterija roda Klebsiella bila je za ampicilin 90,9%, kloramfenikol 72,7%, ciprofloksacin 54,5%, enrofloksacin 90,9%, neomicin 63,6%, norfloksacin 63,6%, streptomicin 81,8% i tetraciklin 81,8%. Izolati Salmonella spp. pokazivali su otpornost na ampicilin (80,0%), kloramfenikol (80,0%), enrofloksacin (20,0%), neomicin (80,0%), norfloksacin (20,0%), streptomicin (80,0%) i tetraciklin (35,0%), ali su u potpunosti bili osjetljivi na ciprofloksacin. Izolati Enterobacter aerogenes su bili otporni na ampicilin (81,3%), kloramfenikol (75,0%), ciprofloksacin (6,3%), enrofloksacin (18,8%), neomicin (37,5%), norfloksacin (25,0%), streptomicin (56,3%) i tetraciklin (75,0%). Sveukupno je 147 (79,9%) od 184 izolata pokazivalo visestruku otpornost na najmanje tri nesrodna antimikrobna lijeka. Veliki postotak bakterijskih izolata iz slobodno drzanih pilica na antimikrobne lijekove moze biti od znatne vaznosti za ljudsko i zivotinjsko zdravlje s nepovoljnim gospodarskim ucinkom. Kljucne rijeci: visestruka otpornost na lijekove, Enterobacteriaceae, slobodno drzani pilici