Background/aim: Biofilm formation is a major determinant factor in the development of urinary tract infections (UTIs) by uropathogenic Escherichia coli (UPEC). Several adhesion factors are involved in attachment of bacterial cells to the urinary tract and biofilm development. Materials and methods: The possible relationship between different adhesion factor genes (AFGs) and biofilm formation among UPEC isolates was investigated. Prevalence of different AFGs including fimA, fimH, papAH, papC, papEF, sfa-S, foc/G, and bmaE and their association to biofilm formation were investigated. Phenotypic expression of type 1 and P fimbriae was also investigated. Results: Our results showed that 84% of UPEC were moderate to strong biofilm producers. Prevalence of the type 1 and P fimbriae associated genes (fimA, fimH, papEF, papC) as well as the F$_{1}$C fimbriae gene (foc/G) did not show a difference among different biofilm-producing groups, while higher prevalence of papAH, bmaE (M fimbriae), and sfaS (S-fimbriae) was observed for the strains producing moderate to strong biofilms. Phenotypic expression of type 1 fimbriae was associated with biofilm formation, while no association was observed for P fimbriae. Conclusion: Different AFGs (especially M and S fimbria) and their expression levels affect the biofilm formation ability of UPEC.