This Safety Guide provides recommendations on the safe disposal of disused sealed radioactive sources in borehole disposal facilities. Sealed radioactive sources are used all over the world for a wide range of purposes, in areas such as health, industry, research and agriculture. These sources are usually managed safely while in use, but States often experience challenges in their management once the sources reach the end of their useful lives. Even though they may no longer emit sufficient radiation for their intended purpose, disused sources are radioactive and potentially hazardous, and they need to be managed as radioactive waste. Written for regulators and others involved in the development and management of borehole disposal facilities, the objective of this Safety Guide is to provide recommendations on the commissioning, operation, closure, institutional control and regulation of borehole disposal facilities for disused sealed radioactive sources, and small volumes of low and intermediate level secondary waste generated during the management of these sources. This Safety Guide can also be used as a basis for reassessing and, where appropriate, upgrading the safety of existing borehole disposal facilities.