In response to an increasing level of aggression experienced by health care staff in the workplace, the then Secretary of State for Health launched a campaign tackling violence against staff in the National Health Service (Dobson 1998). Occupational therapists recognise aggression as a symptom often following a brain injury and as a potential barrier to rehabilitation. This study explored how occupational therapists perceived and managed aggression with adults post brain injury. A grounded theory qualitative research methodology was used. A purposive sample of 15 occupational therapists working with adults with a brain injury participated in semi-structured audiotaped interviews. The data analysis identified that the participants experienced and perceived aggression as verbal, physical and gestural. The findings suggest that occupational therapists need to increase their awareness of the problems associated with aggression. The study identified that in the presence of the elements of close physical contact or fear, and where adults with a brain injury were unsure about what was going to happen next, aggression was more likely to take place. It appears necessary to explore further why this is and to establish strategies to reduce the perceived threat to adults with a brain injury and the potential risks to therapists.