In order to reveal the antimicrobial resistance profiles against first-line antimicrobial agents in community-acquired acute uncomplicated urinary tract infections (UTIs), resistance patterns were determined for 1664 Escherichia coli strains collected between 2004 and 2006 in GATA Haydarpasa Training Hospital, Istanbul, Turkey. Of the isolates 38.2% were found to be susceptible to all of the tested antimicrobial agents, while the resistance rate to single antibiotic was 13.5%. Highest prevalence of antimicrobial resistance was observed for ampicillin (AMP) (49%), followed by amoxycillin-clavulanic acid (AMC) (34%), sulphamethoxazole/trimethoprim (SXT) (34%) and ciprofloxacin (CIP) (18%). The rate of multidrug resistant isolates was 33.5% and 48.4% of them were co-resistant. Resistance against two antimicrobials was identified in 244, against three antimicrobials in 205, against four antimicrobials in 160, against five antimicrobials in 63 and against six antimicrobials in 23 strains. Most frequent phenotypes indicating resistance against two, three and four antimicrobial agents were AMP/AMC (5.7%), AMP/AMC/SXT (5.4%) and AMP/AMC/cephazolin/SXT (2.6%), respectively. Extended spectrum beta-lactamase (ESBL) activity was detected in 40 (2.4%) of the isolates. Most prominent increases in resistance prevalence during the study period were observed for AMP (from 52% to 63%), AMC (from 33% to 45%) and CIP (from 15% to 22%). These results show that resistance to AMP, AMC and SXT are frequent in community-acquired E.coli strains and empirical initial treatment with these agents will most probably be inappropriate in our region.