Abstract: The guidelines recognise that the assessment and treatment of substance misusers present forensic physicians with particular challenges that require certain skills and experience to ensure appropriate management. They stress the importance of good communication, of working closely with custody officers and of shared responsibility for the safety and care of detainees with substance misuse. In particular, they stress the importance of : the full participation of forensic physicians in all aspects and at all stages of the healthcare of detainees with substance misuse/dependence providing advice to custody officers and others involved with detainees with substance misuse/dependence comprehensive contemporaneous records appropriate sharing of information in accordance with the law and the General Medical Council’s advice on professional confidentiality being aware when making all interventions that the interests of the detainee as a patient are paramount. We believe that these guidelines will be of immense value to all practitioners in helping and supporting detainees and that they will also be useful for teaching purposes for medical and nursing staff and arrest referral officers.