<p>Background: Antibiotic resistant bacteria can be considered as a main problem in infection management. Zinc oxide nanoparticles (ZnO NPs), individually or in combination with antibiotics, can be considered as good candidates for struggling against drug resistant bacteria.<br /> Methods: In this study, Zinc oxide nanoparticles were synthesized using sol-gel method in low temperature as a cost effective procedure and characterized by X-ray diffraction and Scanning Electron Microscopy. Antibacterial activity of 9 new combinations of Zinc oxide nanoparticles and ceftazidime was assessed against standards and new clinically isolated multi drug resistant <em>Pseudomonas aeruginosa (P. aeruginosa)</em>, in order to evaluate enhancement effect of synthesized Zinc oxide nanoparticles on antibacterial activity of ceftazidime.<br /> Results: The results indicated that desirable effects can be seen at 6 and 7 <em>mM</em> of Zinc oxide nanoparticles (60 to 100% inhibition). Moreover, after evaluation of 9 new combinations with various concentrations of both components, it was demonstrated that Zinc oxide nanoparticles can enhance the antibacterial activity of ceftazidime, against some bacterial strains of <em>P. aeruginosa</em>. The highest activity was observed with the concentration of 20 <em>&mu;g/ml</em> ceftazidime in the presence of 5, 6 or 7 <em>mM</em> of Zinc oxide nanoparticles.<br /> Conclusion: Zinc oxide nanoparticles in appropriate concentrations can be proposed as new and promising candidates for overcoming bacterial resistance.</p>