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Background: Pseudomonas aeruginosa is a human opportunistic pathogen which is considered one of the agents causing nosocamial infection. Recent studies have reported increased resistance of Pseudomonas aeruginosa to imipenem. The aim of this study was to determine resistance to antipseudomonal antibiotics including imipenem in Pseudomonas aeruginosa strains. Materials and Methods: In this cross-sectional study, 100 Pseudomonas aeruginosa strains obtained from clinical samples of patients in hospitals in Arak, Iran, were identified and isolated through microbiological methods, including Gram staining, oxidase test, Indol test, and oxidative-fermentative test. Then antibiotic susceptibility test was performed for imipenem, meropenem, gentamicin, amikacin, ciprofloxacin, and ceftazidime by disk diffusion method according to NCCLS (National Committee for Clinical Laboratory Standards) .Minimum inhibitory concentration (MIC) was done for determining imipenem-resistant strains Results: Antibiotic susceptibility test showed that resistance rates to imipenem, meropenem, gentamicin, amikacin, ciprofloxacin, and ceftazidime were 35%, 35%, 14%, 9%, 23% and 15%, respectively. Also, MIC test showed that 30 strains were resistant to imipenem, 27 to ceftazidime, 35 to cefepime, and 35 to ciprofloxacin. Conclusion: The results of this study indicated a high rate of antibiotics resistant of Pseudomonas aeroginosa strains to different antibiotic groups. Therefore, new and more effective methods should be found for controlling Pseudomonas infections and preventing the outbreak of its antibiotic-resistant strains.