We explore the impact of the 2010 World Cup, held in South Africa, on levels of assault attendances to 15 emergency departments in England. The majority (70.1%) of assault attendees during the 2010 World Cup was male and aged 18–34 years (52.5%). Assault attendances increased by 37.5% on the days that England played (P < 0.01). Preparation for major sporting events in non-host countries should include violence prevention activity. Emergency department data can be used to identify violence associated with such events and thus inform both the targeting of prevention efforts and assessments of their effectiveness.