Background and Objectives: The hospital staff is always vulnerable to needle stick injury (NSI). NSI potentially increases the risk of HCV, HBV, HIV, and other infections. This study was implemented with the aim of determining the frequency of NSI in nurses and paramedical staff of the Zanjan district educational hospitals. Materials and Methods: In this descriptive study, 600 nurses and paramedical staff who were working in educational hospitals of Zanjan district for more than 1 year completed a questionnaire. Descriptive and analytical statistic methods were used to analyze the gathered data by using the SPSS ver.16 software. Results: Based on our findings, 53.6% of the respondents had experienced NSI throughout their work period. 26.3% of the participants in the study had the history of NSI within past year. The frequency of NSI had a reverse relationship with age and work history, and it was significantly higher in male workers, technicians, workers of labor unit and operation room, holders of academic degrees on hospital operations, midwifery, and anesthesia, and morning work shift of the hospitals. Injury with the syringe needle was the most frequent (53.8%)cause of the NSI. Only 46.5% of the injured workers had reported the event to the hospital Infection Control Officer. Conclusion: Because of the importance of NSI transmitted infections, better education of the staff, the practice of standard precautions,and also vaccination of the less experienced hospital workers, especiallyin the delivery unit and operation ward staff, is highly recommended.