Abstract : The aim of this study is to identify the genetic convergence between many strains of Pseudomonas aeruginosa that isolated from two different environments clinical samples and water samples. A total of 13 strains of Pseudomonas aeruginosa were collected, six isolates from clinical samples were obtained from patients attending in Al- Ramadi Hospital and seven samples of water from Faculty of Dentistry clinics /University of Anbar. Genotyping was done by employing the ERIC fingerprinting assay. The biofilm formation was tested by using Quantitative biofilm assay. The results of our study found genetic relatedness between the strains according to the molecular analysis of DNA using ERIC-PCR, revealed genetically identical among clinical strains and dental unites waterline strains. The 13 strains were divided in to three classes (I, II and III) according to molecular analysis of DNA results. The class I of P. aeruginosa include (P1, P2, P3, P4, P5, P9, P10 and P11 strains) that isolated from waterline dental unite and clinical samples. The class II of P. aeruginosa include (P8, P12 and P13) were isolated from clinical samples. The class III (P6 and P7) were grouped in the same cluster, these samples were obtained from water samples. Our study found that all isolates were producing biofilm and there are no significant differences between the isolates in forming biofilm (p 0.05). According to the statistic results the study found that class I have the highest ability to produce biofilm