OBJECTIVE: The objective of this scoping review is to describe existing guidance documents or studies reporting on the conduct of meta-analyses in updated systematic reviews (USRs) or living systematic reviews (LSRs). INTRODUCTION: The rapid increase in the medical literature poses a substantial challenge in keeping systematic reviews up to date. In LSRs, a review is updated with a pre-specified frequency or when some other signalling criterion is triggered. While the LSR framework is well-established, there is uncertainty regarding the most appropriate methods for conducting repeated meta-analyses over time, which may result in sub-optimal decision-making. INCLUSION CRITERIA: Studies of any design (including commentaries, books, manuals) providing guidance on conducting meta-analysis in USRs or LSRs. METHODS: This review will use the JBI methodology for scoping reviews. We will search multiple medical bibliographic databases (Cochrane Library, Embase, ERIC, MEDLINE, JBI Evidence Synthesis , and PsycINFO), statistical and mathematics databases (COBRA, Current Index to Statistics, MathSciNet, Project Euclid Complete, and zbMATH), pre print archives (Arvix, BioRxiv, and MedRxiv), and unpublished (or gray) literature sources. Two reviewers will independently screen titles, abstracts, and full-text documents, and extract data. Characteristics of recommendations for meta-analysis in USRs and LSRs will be presented using descriptive statistics and categorized concepts. REVIEW REGISTRATION: Open Science Framework https://osf.io/9c27g.