The article discusses the extension of the CONSORT statement to cluster randomized trials, which are more complex and require additional information for accurate interpretation. Cluster randomized trials involve randomizing groups of individuals (such as families or medical practices) rather than individuals themselves, often due to the risk of contamination or feasibility constraints. The authors highlight methodological issues in cluster trials, such as the reduction in effective sample size due to intraclass correlation and the need for adjustments in sample size calculations. They also note that many published cluster trials have poor reporting, with only a few accounting for clustering in their planning, analysis, or sample size calculations. To address these issues, the authors propose extending the CONSORT statement to include specific information on the rationale for adopting a cluster design, how clustering was incorporated into sample size calculations and analysis, and the flow of clusters and individuals through the trial. They provide examples of good reporting and explain the importance of these extensions for ensuring accurate interpretation of cluster trial results. The article emphasizes the need for journal editors to include these guidelines in their instructions to authors to improve the quality of reporting in cluster trials.The article discusses the extension of the CONSORT statement to cluster randomized trials, which are more complex and require additional information for accurate interpretation. Cluster randomized trials involve randomizing groups of individuals (such as families or medical practices) rather than individuals themselves, often due to the risk of contamination or feasibility constraints. The authors highlight methodological issues in cluster trials, such as the reduction in effective sample size due to intraclass correlation and the need for adjustments in sample size calculations. They also note that many published cluster trials have poor reporting, with only a few accounting for clustering in their planning, analysis, or sample size calculations. To address these issues, the authors propose extending the CONSORT statement to include specific information on the rationale for adopting a cluster design, how clustering was incorporated into sample size calculations and analysis, and the flow of clusters and individuals through the trial. They provide examples of good reporting and explain the importance of these extensions for ensuring accurate interpretation of cluster trial results. The article emphasizes the need for journal editors to include these guidelines in their instructions to authors to improve the quality of reporting in cluster trials.