Brief interventions are psychosocial techniques designed to help recipients recognise harmful patterns of substance use, and to motivate and support them to address that use. Studies suggest that brief interventions in an emergency department maximise the benefit of a unique ‘window of opportunity’ for engaging with people with substance use problems who do not necessarily receive assessment, referral or intervention. This paper considers five systematic reviews and 16 randomised controlled trials and points to the potential benefits of brief interventions, albeit with a need for more research.