The Synthesis Without Meta-analysis (SWiM) guideline provides a reporting framework for systematic reviews that do not use meta-analysis to synthesize intervention effects. This guideline aims to improve transparency in the methods and results of such reviews, which are commonly used when meta-analysis is not possible or appropriate. The SWiM guideline includes nine reporting items that address key aspects of the synthesis process, including study grouping, standardized metrics, synthesis methods, criteria for prioritizing results, investigation of heterogeneity, certainty of evidence, data presentation, reporting of results, and limitations of the synthesis. The guideline was developed through a rigorous process involving expert consultation, Delphi surveys, and pilot testing. It is intended to complement existing reporting guidelines such as PRISMA and is particularly relevant for reviews that incorporate diverse data sources not amenable to meta-analysis. The SWiM items are designed to ensure that the synthesis methods and results are clearly reported, allowing readers to assess the validity of the review findings. The guideline emphasizes the importance of transparency in reporting synthesis methods, including the rationale for study groupings, the choice of standardized metrics, and the justification for synthesis methods used. It also addresses the limitations of the synthesis and how they affect the conclusions drawn from the review. The SWiM guideline is not intended for use in reviews that synthesize qualitative data, for which other reporting guidelines are available. The guideline is intended to support authors, journal editors, and readers in assessing the quality and validity of systematic reviews that do not use meta-analysis.The Synthesis Without Meta-analysis (SWiM) guideline provides a reporting framework for systematic reviews that do not use meta-analysis to synthesize intervention effects. This guideline aims to improve transparency in the methods and results of such reviews, which are commonly used when meta-analysis is not possible or appropriate. The SWiM guideline includes nine reporting items that address key aspects of the synthesis process, including study grouping, standardized metrics, synthesis methods, criteria for prioritizing results, investigation of heterogeneity, certainty of evidence, data presentation, reporting of results, and limitations of the synthesis. The guideline was developed through a rigorous process involving expert consultation, Delphi surveys, and pilot testing. It is intended to complement existing reporting guidelines such as PRISMA and is particularly relevant for reviews that incorporate diverse data sources not amenable to meta-analysis. The SWiM items are designed to ensure that the synthesis methods and results are clearly reported, allowing readers to assess the validity of the review findings. The guideline emphasizes the importance of transparency in reporting synthesis methods, including the rationale for study groupings, the choice of standardized metrics, and the justification for synthesis methods used. It also addresses the limitations of the synthesis and how they affect the conclusions drawn from the review. The SWiM guideline is not intended for use in reviews that synthesize qualitative data, for which other reporting guidelines are available. The guideline is intended to support authors, journal editors, and readers in assessing the quality and validity of systematic reviews that do not use meta-analysis.