Introduction. One of the most important resistant mechanisms in Gram-negative bacteria is extended spectrum β-lactamases (ESBLs). Harbour-related genes on plasmids, increase the risk of resistance transmission among commonly reported hospital infections.Aim. This study was designed to explore the dissemination of Pseudomonas aeruginosa producing ESBLs on their plasmids recovered from the different wards of Amir-Al-Momenin burn center, Affiliated with Shiraz University of Medical Sciences.Methodology. Among 256 isolates, 88 (34.38 %) P. aeruginosa strains were isolated from burn hospitalized patients. Samples were processed for antibiotic resistance using the Kirby-Bauer method while MIC was performed for colistin. MIC was used by the microdilution broth method as recommended by Clinical and Laboratory Standards Institute guidelines. Related studied genes were evaluated on extracted plasmids by the PCR method.Results. According to the phenotypic and molecular steps, a total of 58 (65.91 %) and 74 (84.10 %) strains detected positive ESBLs, respectively. Based on antibiogram tests, a total of 63 (71.59 %) isolates were detected as multidrug resistant. All ESBL P. aeruginosa isolates showed identical antimicrobial susceptibility profiles. The genotypic prevalence of ESBLs for bla SHV, bla TEM, bla GES, bla OXA-10 and bla PSE genes was 47.73, 78.41, 5.58, 3.41, 4.55 %, respectively.Conclusion. All P. aeruginosa strains producing ESBLs had plasmids containing related genes. The data indicated a high prevalence of ESBL among P. aeruginosa isolates in the southwest of the Iran burn center and their enzyme types were diverse.