Background: Carbapenem resistant Klebsiella species [CRK] is increasing worldwide that may necessitate the use of combination therapy of antibiotics. Objectives: our aim was to characterize the main mechanisms of resistance carried by CRK isolates and to investigate the in-vitro efficacy of antibiotic combinations. Methodology: One hundred Klebsiella isolates were used for detection of KPC by modified Hodge test and boronic acid combination disc. PCR was done for detection of (OXA-48, KPC, OMP-35 and OMP-36) genes. The efficacy of antimicrobials combination against these isolates was also tested. Results: By boronic acid combination disc 62% were positive, by modified Hodge test 12% were positive. By PCR; 18% of isolates were positive for OMP-35, 16% for KPC, 14% OXA-48 and 6% for OMP36 genes. Antibiotic combination results showed that 64 and 26 isolates were sensitive to gentamicin- ciprofloxacin, meropenem-ciprofloxacin combinations respectively. Conclusion: We concluded that OXA-48, KPC, OMP-35 and OMP-36 genes were circulating in our hospital. Gentamycin and ciprofloxacin Combination may be effective.