Adolescent risk-taking and aggressive behaviours are among the most visible forms of violence in society. A study was carried out to identify the prevalence and risk factors for aggression, violence and criminal behaviour among adolescents in Alexandria, Egypt. Using multistage, cluster sampling of families from all health districts in Alexandria, the mothers of 783 adolescents aged 11–19 years answered an Arabic version of the Mentor Research Institute screening questionnaire. Overall 26.9% of adolescents were assessed to be at high risk and 20.2% at extremely high risk of aggression and criminal behaviour. Living in urban/slum areas, male sex, low level of parents’ education/occupation, exposure to violence within the family and changes in behaviour of any family member were associated with risk of aggression/violence. In multivariate analysis, the significant independent variables were adolescents’ sex, presence of behavioural changes in the family, violence against brothers and sisters and substance abuse by any family member.