Pseudomonas aeruginosa strains, especially multidrug resistant, have great of importance among nosocomial infection isolates. Production of beta lactamase is an important mechanism in gram-negative bacteria for resistance to beta-lactam antibiotics. PER-1 enzyme is derived from an extended spectrum beta-lactamase that is non-TEM, non-SHV-derived in class A and especially causes ceftazidime resistance. In this study, our aim was to investigate the relationship between CLASS-1 integrons and PER-1 enzyme in ceftazidime-resistance Pseudomonas aeruginosa. The PER-1 type beta lactamase enzyme that causes ceftazidime-resistance, determines the frequency, and detects the relationship between the enzyme and CLASS-1 integrons by PCR in 100 (one hundred) ceftazidime-resistant Pseudomonas aeruginosa (P. aeruginosa) isolated at Ondokuz May?s University Hospital (Turkey) between 2007 and 2008. In this study, blaPER-1 was detected in 40% (40/100) of the isolates. Four principal clones, which were detected in P. aeruginosa strains were responsible for high prevalence using Random Amplified Polymorphic DNA-PCR (RAPD-PCR) methods. CLASS-1 integron was detected in 62.5% (25/40) of the PER-1 enzyme bearing strains and association between blaPER-1 and CLASS-1 integrons were shown in 2 (two) Pseudomonas aeruginosa strain. Also resistance rates of PRL antibiotic in blaPER-1 negative group was found to be significantly higher against blaPER-1 positive group, resistance rates of other antibiotics were no different between these two groups. We concluded that PER-1 enzyme is common in our hospital and their clonal diversity indicates horizontal dissemination, the association between bla PER-1 and CLASS-1 integrons can accelerate dissemination of this gene.