The aim of the study was to evaluate the frequencies of the bacterial pathogens responsible for urinary tract infections (UTIs) and their susceptibility patterns. In this study, 4244 bacterial strains isolated from urine cultures were examined in the period from January 1999 to February 2000. Of the 4244 strains, 1279 and 2965 were isolated from the outpatients and the inpatients, respectively. Identification of bacteria and antimicrobial susceptibility testing were performed by using Sceptor System (Becton Dickinson, USA). Of isolates, 65% were Gram-negative bacteria (GNB). Escherichia coli was the most common strain (35% of the overall strains; 48% in outpatients, 29% in inpatients). However, Enterococci were the most common Gram positive bacteria (GPB) (19% of the overall strains; 9% in the outpatients, 23% in the inpatients). For E. coli and other Enterobacteriaceae spp., the susceptibility rates (%) were as below; for amikacin 97-82, for cefotetan 93-85, for imipenem 92-92, for ceftriaxone 88-58, for nitrofurantoin 86-37, for gentamicin 84-59, for ceftazidime 80-52, for cefazolin 78-34, for ciprofloxacin 69-65,for ticarcillin/clavulanic acid 51-44, for amoxicillin- clavulanic acid 47-32, for trimethoprim/sulfamethoxazole 39-46, for ampicillin 36-7, for piperacillin 34-30, respectively. Imipenem was the most effective antibiotic for Pseudomonas and Acinetobacter strains. Of enterococci, 3.50% were resistant to vancomycin. For Coagulase-negative staphylococci (CNS) and Staphylococcus aureus, the rates of resistance to methicillin were 29% and 50% in outpatients; 30% and 78% in inpatients, respectively. Data presented in this study indicated that the resistance to antibiotics is common among bacteria responsible for UTIs in both of outpatients and inpatients in our hospital. We concluded that it is important to follow-up the frequencies of local pathogens and their resistance rates to antimicrobials to perform the optimal therapy for patients with UTIs.