In an effort to improve safety in psychiatric settings, health professionals need to be aware of patients at risk for aggression and violent behaviour. To do so, a risk-flagging functionality can be built into an electronic health record system to alert health professionals of potentially aggressive or violent patients. This paper describes a risk-flagging system at Canada's largest psychiatric hospital and presents initial findings and lessons learned. Risk flags embedded in an electronic health record system are one way of communicating patient risks to health professionals but should be complemented with other forms of risk communication.