In this study,in vitro susceptibilities of E.coli,Klebsiella and Pseudomonas aeruginosa strains isolated from hospitalized patients were tested against various antibiotics such as ampicilin, amoxicillin /clavulanate, ceftriaxone, cefotaxim, ciprofloxacin, amikacin, trimethoprim/sul-famethoxazole and imipenem by disk diffusion test. The resistance rate of isolates to ampicillin and trimethoprim/ sulfamethoxazole were found to be high.Carbepenems, quinolones and 3 th and 4 th generation cephalosporins were the most effective antibiotics against isolates.