Abstract: Workplace violence is still a problem that nurses may be exposed to in clinical wards. A psychiatric ward is among the most probable one confronting this violence. This study determined the workplace violence in psychiatric wards in Tehran, Iran. Nurses working in Razi Psychiatric Center, Tehran, Iran were enrolled using the International Workplace Violence questionnaire. Among 385 nurses of this ward, 200 subjects completed the questionnaire using a simple random sampling method with a response rate of 91.5%. The prevalence of workplace violence was 71% including mental (93.4%) and physical violence (71.6%). Verbal and sexual violence occurred in 19.1 and 5.5% of subjects, respectively. The 62.3% of the nurses did not report violence because they considered it useless (55.3%) or did not believe to be important (42.1%). The 61.2% believed to the necessity of training courses while 72.7% had completed these courses and 59.6% believed to a reporting system. The need to security guard (56.8%), taking security actions in wards (67.8%) and training of staffs (68.9%) were the most important preventive measures reported to be effective for workplace violence. It seems that training courses, establishing rules to prevent workplace violence, reporting systems, compensating losses from violence, increasing the security at workplace, increasing the number of nurses and providing especial guiding protocols against any workplace violence would promote the wards to control the workplace violence against nurses.