Background and Objective: Nosocomial infections, with their associated increased hospital mortality and hospitalization costs, are discussed as one of the major health problems in communities. Urinary tract infections are known as the most common nosocomial infection that makes up over 40% of all hospital infections. In this study, the role of antibiotics usage before admission to the intensive care unit (ICU) and the frequency of urinary tract infections during ICU stay were studied. Materials and Methods: This prospective cross-sectional study was done on 353 patients admitted to the ICUs of Besat and Ekbatan Hospitals in Hamedan. Following up their weekly visits to the ICU, the Patients with urinary tract infections were identified during weekly visits to the ICUs, and variables including the type of antibiotic taken prior to the occurrence of UTI, and the organisms causing the infection were recorded. Data analyses were performed by SPSS program Chi-Square and Fisher exact tests. Results: Among the 353 patients studied, with mean age of 51.2 ± 21.9 years, 61 (17%) were suffering from nosocomial UTI. Most of them [19 patients (31.1%)] were over 65 years. The urine cultures were positive in 20% of the patients. Gram-negative and -positive bacteria, and fungi made up 41.7%, 33.3%, 25%of the infection cases, respectively. Eighty-five percent of the cases had received antibiotics prior to developing nosocomial UTI, and 55% of the taken antibiotics belonged to the cephalosporin group. Furthermore, 44% of the cases had taken more than one type of antibiotics. There was a significant relationship between the type of microorganism responsible for the infection and the type of antibiotic taken before admission to the ICU (P=0.011). Conclusion: In this study, the frequency of nosocomial UTI was estimated at 17%, and it was found that taking inappropriate/unnecessary antibiotics before entering the ICU had a significant relationship with occurrence of nosocomial UTI. Therefore, educating the public for avoiding unnecessary consumption of antibiotics seems necessary.