Background: Pseudomonas aeruginosa (P.aeruginosa) is one of the most commonbacteria capable of forming biofilms which are important in the establishment of P. aeruginosa infections on different host tissues includingpostoperative wounds. P. aeruginosa possesses at least two well-defined, interrelated QS systems, las and rhl that control the production of different virulence factors including biofilm development.Objectives: To determine the antimicrobial susceptibility pattern, biofilm producing ability and the presence of QS lasR gene in isolated P. aeruginosa strains from patients withpost-operative wound infections.Methodology:The study was conducted on Fifty-four clinical isolates of P. aeruginosa from infected postoperative wounds in patients admitted in Zagazig university hospitals, Egypt. Isolates from all patients were tested for antimicrobial susceptibility using disk diffusion method, in vitro formation of biofilm in microtiter plates containing Tryptone Soya Broth (TSB) medium and detection of QS lasR gene using conventional PCR technique. Results: P. aeruginosa isolates showed high prevalence of resistance against ceftazidimeand aztreonam (74.1%), while they showed the lowest resistance to ceftolozan/tazobactam (7.4%). Biofilm formation was detected in 38 (70.4%) of P. aeruginosa isolates; 14.8%, 46.3% , 9.3% and 29.6% of isolates were strong, moderate, weak and non-biofilm producers, respectively. The lasR gene was detected in 42 (77.8%) of P. aeruginosa isolates. There was significant relation between biofilm formation and presence of lasR gene. Conclusion:Postoperative wound infection may serve as a reservoir for multidrug resistant biofilm forming P. aeruginosa. The QS lasR gene is strongly associated with biofilm formation,which can help in identifying lasR gene as a useful diagnostic marker for biofilm producing P. aeruginosa strains isolated from infected wounds.