The purpose of this prospective study was to identify attitudinal changes and to describe the emotional, cognitive, social, and biophysiological short- and long-term reactions of nursing staff being physically assaulted by a patient. Sixty-one assaulted nursing staff at the University of California Los Angeles Neuropsychiatric Institute comprised the sample. Responses to the assault were elicited through weekly self-report questionnaires and interviews at week 1 and week 6. Follow-up questionnaires were completed at 6 months to 1 year following the assault. Sixty-seven percent (41/61) of the staff met the "responder" criteria during week 1. Eighteen percent (11/61) of the assaulted staff continued to experience moderate to severe responses 6 weeks following the assault. Long-term follow-up showed that 21% (8/39) of the staff were responders at 6 months, and 16% (4/25) were responders at 1 year. Two overall trends were evident: an overall decrease in the frequency of moderate to severe responses in each of the four categories from weeks 1 to 6, with increases during weeks 3 and 4, and a higher frequency of moderate, rather than intense and severe, responses throughout the 6 week period. No significant changes in attitudes were found. The data support the need for formalized clinical, educational, and administrative programs to assist staff in coping with this stressful work experience.