Introduction: It has been shown that biofilm formations are responsible for many human infections, especially in chronic infections. Pseudomonas aeruginosa (p.a) is an opportunistic human pathogen, its biofilm has serious negative effects on the health of patients with immune-suppresser e.g. cystic fibrosis individuals. p.a drug resistance, a worldwide concern is increasing and biofilm-forming potential is an increasing factor. Materials and Methods: One-hundred-fifty clinical P.a isolates were collected from Mustafa hospital in Ilam, then their resistance against several β-lactam antibiotics that high consumption in the medical prescription was assessment. Also, biofilm formation was tested by microdilution and microtiter plate methods, respectively. Results: There are abilities biofilm formations among the resistances isolates to the most tested antibiotics. But, we observed only a significant correlation between resistance to ceftazidime (P=0.003) and meropenem (P=0.002) with biofilm formation, both in resistance and sensitive isolates. Conclusion: Biofilm caused by Increasing drug resistance in the world, as β-lactam antibiotics, will be caused a creating complication  P.a infection treatment. Moreover, biofilm can form antibiotic-resistant strains and increases many infections in the future. As a result, more studies for founding new drugs against biofilm formation mechanisms are necessary.