The objective was to assess the impact of new guidance on the conduct of narrative synthesis in systematic reviews of effectiveness, by means of a blinded comparison of guidance-led narrative synthesis against a meta-analysis of the same study data.The conclusions of the two syntheses were broadly similar. However, differences between the approaches meant that conclusions about the impact of moderators of effect appeared stronger when derived from the meta-analysis, whereas implications for future research appeared more extensive when derived from the narrative synthesis. These findings emphasize that a rigorously conducted narrative synthesis can add meaning and value to the findings of meta-analysis.The guidance framework provided a useful vehicle for structuring a narrative synthesis and increasing transparency and rigour of the process.While there may be risks with overinterpretation of study data, the framework, tools and techniques described in the guidance appear to increase the transparency and reproducibility of narrative synthesis.