This 1-year retrospective study was conducted on a regional secure unit at the Bethlem Royal Hospital, London, using the hospital's data collection sheet for violent incidents. The majority of incidents were minor in nature but there were a few assaults that involved pain, lacerations or bruising. Although violence was common to the majority of patients, two contributed a large number. Those staff at the bottom of the nursing hierachy who spent most time with patients were most at risk. Likewise fellow patients were also often involved in incidents. Violence did not tail off after the breakfast period, as reported in previous studies, but continued to rise until bedtime.