Introduction: Because of their ongoing contact with patients, nurses have an important role in maintaining and improving standards of patient safety, in which nurses’ workplace condition may have impact on the incidence of nosocomial infections and may endanger patient safety. Aim: the aim of this study was to investigate the relationship between nurses' workplace environment and nosocomial infection.

Methods: This descriptive - correlational study was done on 300 nurses working in teaching hospitals in Tehran, Iran. Subjects were selected through stratified sampling method. Data related to nurses' workplace environment were collected by Nurses Work Environment Index (NWI). Its validity and reliability was determined by content validity and Cronbach's alpha (0/89), respectively. Data related to nosocomial infection were extracted from INIS software. Collected data were analyzed using descriptive statistics and inferential analysis (Pearson’s correlation test) by SPSS (ver.16) software.

Results: The result showed that the mean incidence of nosocomial infections in the selected hospital was 3.47%, and urinary tract infection (UTI) was the most common infection in these hospitals (39.7%). Pearson's correlation analysis showed that there was a significant negative relationship between each domain of nurses' work environment and the incidence of nosocomial infection (p<0.05).

Conclusion: It was found that there was a negative correlation between nurses' work environment and nosocomial infection. Therefore, one of the important strategies for decreasing of nosocomial infection and promotion of patients’ safety is the improvement of the work condition of health care professionals, especially nurses’ work environment.