The present study included collecting of 125 clinical bacterial isolates from different sources such as pus, sputum, nasal polyps, urine and blood. The collected bacterial isolates were preliminary identified by biochemical tests as 44 Pseudomonas spp., 35Klebsiella spp., 18E. coli, 17 Acinetobacter spp., 8 Proteus spp. and 3Enterobacter spp., The test for biofilm formation in these isolates was carried out by using three different methodsthat finally resulted in 27 positive biofilm forming isolates. Production of quorum sensing signal molecules (acyl homoserine lactone) was detected in 20 isolatesusing gas chromatography mass spectrum (GC/MS); These isolates were 3 Pseudomonas spp., 6 Klebsiella spp., 8 E. coli and 3 Enterobacter spp.,The anti-biofilm activity of some plant extracts was carried out using tube method. It showed that Syzygiumaromaticum was the most effective one and inhibited biofilm formation in all isolates followed by Allium sativum.Syzygiumaromaticum extract also inhibited quorum sensing production in the selected 20 bacterial isolates. From the above results,Syzygiumaromaticumextract was recommended to be used as an active antibacterial agent against multidrug resistant bacteria due to its ability to inhibit biofilm formation and quorum sensing signal production.Finally, the most potent bacterial isolates were genetically identified by 16S rRNA gene sequencing.