Emergency nurses are at higher risk for workplace violence than other health care workers, so a workplace violence prevention program is crucial to prevent violence. Therefore, the purpose of this study the effectiveness of workplace violence prevention program on the rate of violence, knowledge, attitude and practice of nurses towards patients and their companions violence in the emergency department of selected hospital in Tehran. This study applied a quasi-experimental design using control groups and pre- and post-tests. The research units included 48 nurses working in the emergency department of Farabi Hospital in Tehran. The intervention included the use of a program featuring some management issues such as applying ventilation, using closed-circuit television cameras, modifying lightings, employing a security guard for the evening shift, and training. The training, which will be entitled “Management and Prevention of Workplace Violence,”will be entitled as a 2-day workshop using training programs. Data will be collected by 1.”International Workplace Violence Questionnaire”. 2. Nurse's Knowledge, Attitude and Practice Toward Workplace Violence Questionnaire”.Control group,The training, which will be entitle “Management and Prevention of Workplace Violence,” will be implemented a one-day workshop using training programs.