P. aeriogenosa is an opportunistic pathogen frequently associated to nosocomial infections ,especially in immunocompromised hosts.Biofilm production is an important mechanism for the survival of Pseudomonas aeruginosa and its relationship with antimicrobial resistance represents a challenge for patient therapeutics . Pseudomonas aeruginosa is an opportunistic pathogen frequently associated to nosocomial infections ,especially in immunocompromised hosts.The aim of this study to assess the role of some selected genes and the formation of biofilm in clinically isolates of drug resistant Pseudomonas aeruginosa.This study included 35 patients who were admitted in different inpatient departments at a Benha University Hospital and Benha Children Hospital during the period from August 2018 to December 2019.The samples were tips of indwelling medical device and urine samples were taken from patients using urinary catheters. These isolates were tested from antibiotic sensitivity by disk diffusion method and were screened phenotypically for biofilm formation by Congo Red Agar (CRA) method and Tissue Culture Plate (TCP) technique .The antibiogram of all isolates was determined and reveald that (XDR were 54.3%) ,(MDR were 8.6%)and (Non MDR/XDR were 37.1%). The presence of RhlI and PelB genes in biofilm forming P. aeruginosa isolates was tested by using polymerase chain reaction (PCR).The results revealed the presence of these genes in both strong and weak biofilm producer isolates.These final results showed the significance of these genes in biofilm formation and suggest the presence of other factors which may contribute in determining the degree of biofilm formation in P. aeriogenosa.