Background: The Cochrane Collaboration attempts to avoid duplication of effort by publishing only one systematic review (SR) per topic of interest. However, there are often many non-Cochrane reviews published on the same topic. Objectives: To quantify and describe the overall body of SR evidence published in different clinical areas, including an analysis of Cochrane and non-Cochrane SRs that overlap in content. Methods: We chose five topics (eczema prevention, bronchiolitis, alcohol withdrawal, acute severe asthma, procedural sedation) and searched for all Cochrane and non-Cochrane SRs that met pre-defined inclusion criteria. We extracted data on the scope, methods, included studies, results, conclusions, year of publication, and quality of each relevant SR. Results for eczema prevention are presented here. Complete data for other topics will be presented at the Colloquium. Results: There were 30 SRs published on eczema prevention. Six Cochrane SRs included a total of 65 trials and 24,541 subjects; 24 non-Cochrane SRs included 806 studies and 945,234 subjects. Fifteen interventions were examined across the 30 SRs, and five interventions were examined in four or more SRs (including a Cochrane SR; see Table 1). In each cluster the Cochrane SR was never the most recent but was often the highest quality SR (as assessed by AMSTAR). It was not uncommon for overlapping SRs to have discordant results and conclusions. Conclusions: For each SR, it is important to examine the characteristics (population, intervention, comparator, outcomes, study designs, setting), quality (using AMSTAR), and included studied to determine the amount and nature of the overlap across SRs. Some SRs that included a large proportion of overlapping studies came to entirely different conclusions, while other SRs that included very different studies came to similar conclusions. The large number of SRs published in a single topic area indicates duplication of effort and warrants further examination. These findings also have implications for inclusion of non-Cochrane SRs in overviews of reviews. Restricting overviews to Cochrane SRs may not provide a comprehensive synthesis of all treatment options.