Background: Uropathogenic E. coli (UPEC) is by far the most common cause of urinary tract infections (UTIs) worldwide . The degree of pathogenicity is dependent on the presence of virulence factors; however the clinical aspects of such facto rs are not yet fully understood. Objectives: The aim of this study was to assess the prevalence of virulence determinants in UPEC of urinary tract infected subjects and commensal fecal E. coli isolates of healthy individuals. Methodology: A total of 208 patients with clinically diagnosed UTIs were included in the study, 170/208 yielded significant bacterial growth. One hundred fifty five E. coli isolates (100 UPEC from patients with suspected UTIs, 50 commensal fecal E. coli and 5 urinary E. coli isolates from apparently healthy individuals with significant asymptomatic bacteriuria) were investigated phenotypically for α-hly, cnf 1, in vitro biofilm formation and P fimbrae. Four urovirulence genes (hly A, cnf 1, aer and pap C ) were investigated by PCR. Results: α-Hly & cnf 1 virulence factors and their corresponding genes were significantly(P= 0.001) detected in UPEC isolates compared with fecal E. coli isolates, with insignificant difference in phenotypic expression of p fimbrae and PCR assay of aer & pap C genes. Conclusion: the studied virulence determinants are involved in both pathogenesis of UTI and in the ability of E.coli to survive either in intestine or in the new ecological niches such as the human urinary tract.