Nosocomial urinary tract infections (NUTI) which are usually in the first rank in health care associated infections, significantly influence mortality, morbidity, hospitalization period and cost. In this retrospective study, it was aimed to analyze the risk factors in NUTI and also to investigate the effect of urinary catheter application on the distribution of pathogens in patients with NUTI. The study included 1236 NUTI episodes in 1103 patients (age range: 18-95 years; 641 female, 462 male) between January 2000-December 2006. Diagnosis of NUTI was agreed according to CDC criteria. Asymptomatic UTI (urinary tract infection) and other UTIs were excluded and only symptomatic UTI was evaluated. Of NUTIs, 87.9% (1086/1236) were found to be associated with urinary catheter use. No statistically significant difference by means of age, gender and mean interval between admission date and date of determination of infection was determined between the two patient groups, with and without urinary catheter (p>0.05). However, catheter associated NUTI development was statistically significantly higher in intensive care unit patients than patients in other wards (p<0.001). Respiratory failure, unconsciousness, multiple trauma, surgery, central vascular catheter, tracheostomy, mechanical ventilation and peritoneal dialysis were observed more frequently in patients who developed catheter-associated NUTIs (p<0.001). Escherichia coil was isolated in 23.6%, Candida albicans in 18% and non-albicans Candida spp. in 11% of the NUTI episodes. When all Candida species were taken into consideration, they were the most frequent causative agents of NUTI. C. albicans was the most frequent agent in catheter-associated NUTI and E. coli in non-catheter-associated NUTI, their isolation rates being statistically significant (p=0.007 and p=0.005, respectively). No statistically significant difference was detected in the distribution of the other organisms in the two study groups. These data revealed that in urinary tract infections Candida species have replaced the first rank which was occupied by E. coli previously.