The purpose of the present study was to determine the prevalence of aggressive behaviours by patients against nurses in the first year of practice, and to determine the psychological impact of this behaviour. An anonymous survey was sent to registered nurses in their first year of practice. From the 1169 survey instruments that were distributed, 551 were returned completed (a response rate of 47%). The most common inappropriate behaviour by patients involved verbal threats (n = 192, 35%), verbal sexual harassment (n = 167, 30%) and physical intimidation (n = 161, 29%). There were 22 incidents of assault requiring medical intervention and 21 incidents of participants being stalked by patients. Male graduates and younger nurses were especially vulnerable. Mental health was the service area most at risk. A most distressing incident was described by 123 (22%) of respondents. The level of distress caused by the incident was rated by 68 of the 123 respondents (55%) as moderate or severe. Only half of those who described a most distressing event indicated they had some undergraduate training in protecting against assault or in managing potentially violent incidents (n = 63 of 123; 51%). After registration, 45 (37%) indicated they had had such training. The findings of this study indicate priorities for effective prevention programmes. The issues highlighted need to be addressed in undergraduate nursing curricula and in the development of orientation programmes supporting new graduates.