Decommissioning is the last step in the lifetime management of an authorized facility and must be considered during the design, construction, commissioning and operation of such facilities. This Safety Guide provides guidance on how to comply with requirements for the safe decommissioning of medical, industrial and research facilities. It addresses all aspects of decommissioning that are required to ensure safety, such as roles and responsibilities, strategy and planning for decommissioning, conduct of decommissioning actions and termination of the authorization for decommissioning. The intended audience are those individuals involved in policy and strategy development, regulatory control, and planning and implementation of decommissioning.