Nosocomial urinary tract infection (NUSI) is one of the most common hospital acquired infections. In this study, we aimed to determine the risk factors, frequency and the bacterial etiology of NUSI in hospitalized patients at Trace University Hospital, Turkey. Between September 1st 2004 to March 1st 2005, 104 NUSI episodes from 91 adult patients (mean age; 60.8 +/- 16.1 years; 46 were female) were determined among 8704 patients admitted to the hospital. During the study period, cumulative incidence of NUSI was 1.04% and episode rate of NUSI was 1.19%. The most important risk factors for NUSI were detected as urinary catheterization (78.8%), antimicrobial therapy within the previous 15 days (60.6%), fecal incontinence (33.7%) and surgical operations [29.8% (42% of them were urological pertainings)]. In 37.8% of the episodes urinary catheterization was considered as performed unnecessarily. In 26% of the episodes another infection (pneumoniae, abdominal infection, wound infection) accompanied. The causative microorganisms were resistant to the antibiotics used for therapy in 93.6% of the episodes. A total of 118 microorganisms (14 were polymicrobial) have been isolated from the urine cultures. The most frequently isolated ones were Escherichia coil (n: 48; 40.8%), Candida spp. (n: 27; 23%), Enterococcus spp. (n: 13; 11%), Pseudomonas aeruginosa (n: 9; 7.6%), Klebsiella pneumoniae (n: 8; 6.8%) and Acinetobacter spp. (n: 5; 4.2%). The highest susceptibility rates of E. coli isolates were against imipenem and nitrofurantoin (100%) and amikacin (97.7%), the lowest susceptibility rates were against ampicillin (26.7%) and amoxycillin-clavulonate (44.4%). No glycopeptid resistance was detected for Enterococcus spp. while the susceptibility rates to penicilin and nitrofurantoin were 38.5% and 63.6%, respectively. Since the number of the other bacterial species was low (<10) their antimicrobial resistance rates were not evaluated. Extended-spectrum beta-lactamase (ESBL) production was determined in 27% of E. coli and in 25% of K. pneumoniae isolates, and cases with ESBL producing strains had significiantly higher antibiotic consumption rate in the previous 15 days (p = 0.004). Blood cultures which were collected during NUSI episodes yielded positive results in 31.8%. The mortality rate due to NUSI was significantly higher in cases with bloodstream infection (p = 0.000). In conclusion, the high rates of NUSI associated with bloodstream infections and mortality detected have pointed out serious problems in our hospital, and indicated that more attention should be paid on urinary catheterisation, rational antibiotic usage and control of nosocomial infections.