We assessed the susceptibility of Escherichia coli strains causing communityacquired urinary tract infection (UTI) in a large urban center in Brazil, comparing two different populations (patients with health insurance vs. uninsured). 581 nonduplicate strains of E. coli were isolated. The prevalence of antimicrobial resistance was greater than 20% for ampicillin (51%), trimethoprim-sulfamethoxazole (43%), tetracycline (41%) and chloramphenicol (22%). Overall, 12% of the E. coli isolates were resistant to ciprofloxacin. Resistance prevalences to most antimicrobials were similar in the two study populations. Our data provide much needed information on the prevalence of antimicrobial resistance among E. coli causing communityacquired UTI in Brazil. Antimicrobial resistance among strains of E. coli causing community-acquired UTIs was relatively high, particularly resistance to ciprofloxacin.