The antibacterial effects of Cinnamon (Cinnamomum zeylanicum) essential oil and ethanolic extract against extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Pseudomonas aeruginosa strains were studied in the present study. The essential oil and ethanolic fraction of C. zeylanicum showed significant activities against all tested microorganisms and minimal inhibitory concentration values (MIC) of the essential oil ranged from 0.8 to 20.2 μg/ml. The MIC of ethanolic fraction at 60°C were in the range from 8 to 62.12 μg/ml, although at room temperature showed the highest and lowest activity at 14.5 and 64.11 μg/ml, respectively. The results show by these extracts recommends their potential use against multidrug resistant microorganisms. This study also shows that C. zeylanicum could be a potential source of new antimicrobial agents. PCR amplification reaction showed the presence of CTX-M β-lactamases gene in all tested organisms.