This Safety Guide provides specific recommendations on the maintenance, periodic testing and inspection of research reactors to meet the relevant requirements of IAEA Safety Standards Series No. SSR-3, Safety of Research Reactors. It provides guidance on design considerations and recommends good practices in implementing the programme and establishing the organization and responsibilities for maintenance, periodic testing and inspection as well as for the selection, training and qualification of personnel. Procedures, administrative controls and maintenance facilities are also covered as well as procurement and storage of spare parts and components, and testing and inspection methods and techniques used for maintenance, periodic testing and inspection. The recommendations provided in this Safety Guide are aimed at operating organizations of research reactors, regulatory bodies and other organizations involved in a research reactor project. This Safety Guide is a revision of IAEA Safety Standards Series No. NS-G-4.2, which it supersedes.