Introduction: Nosocomial infections are primarily caused by Klebsiella bacteria, which lead to an increase in healthcare costs and the mortality rate. Concerning the alarming increased antibiotic resistance of Klebsiella species, the purpose of this study was to compare the frequency and determine the antibiotic resistance pattern of Klebsiella species isolated from nosocomial infections using Kirby Bauer method. Methods: This study was done on 80 specimens of Klebsiella isolates from 480 hospitalized patients in three different units of Khorramabad Shohadaye Ashayer hospital. After determining the bacterial species, antibiotic-resistance test of Klebsiella species was performed for 15 antibiotics using the disk diffusion method. The results were recorded based on Clinical and Laboratory Standards Institute (CLSI) standard guidelines. Results: The frequency rates of Klebsiella species were determined as follows: Klebsiella pneumoniae (91%), Klebsiella oxytoca (5%), Klebsiella rhinoscleromatis (3%), and Klebsiella ozaenae (1%). The frequency of Klebsiella species on the basis of sources of infection and type of sample respectively were: urine (42%), lung and sputum (36%), wound (15%), blood (6%), and cerebro-spinal fluid (CSF) (1%). The resistance of all Klebsiella species to studied antibiotics were respectively as follows: ceftriaxone (92%), ciprofloxacin (82%), nitrofurantoin (80%), ofloxacin (75%), cefotaxime (70%), imipenem (67%), ticarcillin (66%), nalidixic acid (60%), gentamicin (52%), azithromycin (40%), cefepime (31%), polymyxin B (22%), colistin (17%), amikacin (7%), and meropenem (1%). Conclusion: According to the obtained results, meropenem and amikacin with the lowest resistance are the most effective antibiotics against all Klebsiella strains, and although ceftriaxone antibiotic does not help in the treatment of Klebsiella infections, but it may cause antibiotic resistance.