This study aimed to detect biofilm forming bacteria associated with urinary catheters and to detect genes responsible for biofilm formation. The biofilm formed by bacteria isolated from urinary catheters has been determined by safranine staining. Furthermore, the genes responsible for biofilm formation have been detected by using the PCR technique. A total of 119/150 (79.3%) of clinical isolates obtained from urinary catheters were positive for biofilm formation. The two genes responsible for the biofilm formation, type 3fimbriae (mrkABCDF) gene and type 1 pilus (fimK) gene were detected in the PCR of E.coli and klebsiella isolates, respectively. The two copies of mrpA genes (mr1 and mr2) which control the expression of MR/P fimbriae in proteus species were detected in the PCR products on agarose gel at 1000bp for mr1 and at 850bp for mr2 genes, respectively. In Pseudomonas tox A gene was detected at 200bp. In addition, ica A gene (190bp) and ica D gene (200bp) were detected on agarose gel in PCR products of S. epidermidis and S.aureus isolates at 190bp and 200bp, respectively.