Background: Considering the necessity of hospital infection control because of the long recovery time and increasing the mortality of patients as well as the lack of accurate reports and statistics of some hospitals, the prevalence of nosocomial infections and associated factors were examined in Vasei Hospital of Sabzevar during the years of 2009-2013.Materials and Methods: This study is a descriptive-analytical research. Of 89429 patients admitted during the years of 2009-2013, 1046 cases of patients with nosocomial infections in Vasei Hospital of Sabzevar were studied using SPSS version 22 and chi-square test.Results: According to the result of this study, the prevalence of nosocomial infections in all wards of the hospital was 1.2% (1046 patients), and the prevalence of nosocomial infections based on the type of infection in hospitalized patients was infections of urinary tract, 0.4% (367 patients), respiratory, 0.5% (468 patients), anemia, 0.1% (52 patients), and surgical wounds, 0.3% (277 persons). The most common nosocomial infection was related to the respiratory infections, which is 44% of all infections cases. A significant relationship between age, sex and type of infection was not observed. The most common isolated microorganism was coagulase-negative Staphylococci.Conclusion With accepted prevalence and compare to other studies, the prevalence of nosocomial infections has been reported less than the standard. The results of our research encourage us to standardize the hospital infection reports reported by hospitals as well as solve available problems.