AIM To estimate the effect of nursing, shift and patient characteristics on patients’ aggression in clinical mental health care.DESIGN AND METHODS A follow-up study was performed to estimate the effect of nursing characteristics at shift level and patient characteristics on the incidence of aggression.FINDINGS The incidence of aggression was higher in teams with only female nurses. Teams scoring high on extraversion experienced more verbal aggression and teams scoring high on neuroticism experienced more physical aggression. Younger patients and/or involuntarily admitted patients were more frequently aggressive.IMPLICATIONS FOR PRACTICE Our study is, to our knowledge, the first to investigate the influence of Big Five personality traits of nurses and aggressive behaviour of patients. These findings should stimulate support for nursing teams in order to prevent aggression on psychiatric wards. Information of their personality might serve useful for training purposes.