Int. J. Environ. Res. Public Health 2009, 6 2813 underestimated. Changing society and increasing public awareness and standards of public concern have shifted attention from traditional workplace dangers by physical, chemical, radiological, biological, and ergonomic causes, to focus on psycho-sociological harm, such as workplace violence, sexual harassment, sudden death from overexertion, and work pressure [2,3]. Since workplace harassment, including physical violence (PV), verbal abuse (VA), bullying/mobbing (BM), sexual harassment (SH), and racial harassment (RH), has increased in recent years, in 2002, the United States National Institute for Occupational Safety and Health (NIOSH) vigorously promoted the hope that people around the world would take note of increasing workplace violence [4]. The US Department of Labor, Occupational Safety and Health Administration (OSHA) has also made an effort to establish guidelines for the prevention of workplace violence [5]. Regarding to the national case studies conducted in Australia, Brazil, Bulgaria, and so on, in general hospitals [6] found that the annual prevalence rates of physical PV ranged from 3% to 17%, VA 27.4% to 67%, BM 10.5% to 23%, SH 0.7% to 8%, and RH 0.8% to 2.7%. Using different questionnaires, research conducted in England [7], Hong Kong [8] and China [9] found that PV varied from 5.3% to 21% and VA from 43% to 73%. NIOSH notes that the public place where most such violence can be observed is in hospitals, especially psychiatry wards, emergency rooms, waiting rooms, and geriatric wards [4]. In psychiatry hospitals, the primary care staffs, nurses and nurse aides, are particularly easy targets for psychiatric patients [10,11]. In Taiwan, according to a questionnaire survey conducted on 2003, about 61% of nurses and nurse aides reported being attacked by patients within previous one year in this hospital, but the incidence was still unknown. The risk factors of workplace violence were largely explored in the environmental and patient factors. Viitasara declared that violence was influenced by underlying structural and situational risk factors [12]. Regarding patient profiles, Lowenstein, McNiel, and Nijman stated that patients manifesting higher levels of thinking disturbances, hostile-suspiciousness and agitation-excitement presented higher risk of violence [13-15]. Tiihonen and Wallace found that alcohol-induced psychosis, schizophrenia with alcohol abuse, or co-morbided with personality disorder and substance abuse increased offending behaviors [16,17]. Nevertheless, the risk factors for primary care staff were relatively less explored. Anderson found that staff with abuse history was more vulnerable to physical violence and sexual harassment [18]. Binder said that the role relationship with patients, not the gender was a predictor of violence [10]. In Taiwan, Chou found that young age and shorter duration of employment were the risk factors for violence towards nurses in acute psychiatric wards through a questionnaire survey [19]. The Internet, which is speeding up the progress of every sphere of human life, is now commonly used in Taiwan. A study revealed that the convenience and privacy of the Internet increased the motivation of some people to seek help [20]. The reliability of information provided by clients was high [21]. In addition, a study showed that the questionnaire survey from a website was as reliable as from paper form [22]. Therefore, we used the web-form report system to conduct a one-year follow-up study to determine the incidence rate and risk factors of workplace violence encountered by nursing staff caring for chronic psychiatric patients in Taiwan.