Background and aims: ICUs are faced with increasing rapid emergence of antibiotic- resistant bacteria, which influenc patient mortality. This study was conducted to compare the trend of antimicrobial resistance among microorganism's agents of ICUs nosocomial infections in two periods of 6 months with an interval of 12 months.Methods: In this descriptive analytic study, 322 obtained clinical specimens (including urine, tracheal aspirated materials, blood, wound, synoartrial fluid and chest tube secretion) from 205 hospitalized patients in ICU of Kashani ward Shahrekord, Iran was investigated during two periods of 6 months (second half of 2006 and first half of 2008). Patients with acute inflammatory responses were included in the study. The antibiograme was performed using Disk diffusion method with following disks: ceftriaxone, ceftizoxime, ceftazidime and ciprofloxacin, carbenicillin, norfloxacin, gentamycin, amikacin and co-trimaxazol.Results: The most and less common collected specimens were tracheal discharge (58.6%) and synovial fluid (0.3%) respectively. Overall 24.5% of cultures were positive. (58.2% of tracheal discharge and 0.3% of synovial fluid). Klebsiella and Pseudomonas were the most common isolated bacteria. With an interval of 12 months the resistance trend of isolated bacteria to ceftizoxime, ciprofloxacin and carbenicillin changed from 62.5%, 19%, 100% to 88%, 55%, 71% (P<0.05). There was an increased sensitivity to gentamycin in second period of study.Conclusions: Considering the increasing trend of resistance to ceftizoxime, ciprofloxacin, we recommend them in the case of positive culture and antibiograme. Antibiotic usage in ICU ward must be controlled more effectively and each ICU needs to have a program for antibiotic resistance surveillance.