Abstract Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacterial cell-to-cell communica- tion systems (quorum sensing), which regulate virulence factors production in Pseudomonas aeruginosa, in order to overcome the globalcrisis of antimicrobial resistance. Objectives: Study the potential quorum sensing inhibitory effect of Zinc oxide (ZnO)nanoparticlesin Pseudomonas aeruginosa and the impact on production of virulence factors. Methods: Quorum sensing inhibitory effect of ZnO was evaluated by assessing its ability to reducePseudomonas aeruginosa virulence factors production; rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, qRT-PCR was performed to determine ZnO inhibitory effect onQS-regulatory geneslasI, lasR,rhlI, rhlR, pqsA and pqsR that control virulence factors secretion. Moreover, mice survival test was conducted to investigate the infuence of ZnO on Pseudomonas aeruginosa-induced mortality in vivo. Results: ZnO revealed a statistically signifcant reduction in the production of QS-controlled virulence factors rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, ZnO exhibited a signifcant decrease in the relative ex- pression of QS-regulatory geneslasI, lasR,rhlI, rhlR,pqsA and pqsR. Additionally, ZnO signifcantly reduced the pathogenesis of Pseudomonas aeruginosa in vivo Conclusion: ZnO nanoparticles can be used as a quorum sensing inhibitor in Pseudomonas aeruginosa infections either as an adju- vant or alternative to conventional antimicrobials