This Safety Guide, a companion document to Safety Series Nos 35-S1 and 35-S2, is part of a set of publications in the IAEA Safety Series dealing with all the important areas of research reactor safety which includes Safety Standards, Safety Guides and Safety Practices. This guide presents guidelines, approved by international consensus, for the preparation, review and assessment of the safety documentation (Safety Series No. 35-S1) and for the preparation of the Safety Analysis Report (SAR) (Safety Series No. 35-S2). In addition, it is most applicable during the design and construction stages of research reactors, as well as during relicensing or reassessment of already existing reactors.