Background: Cochrane reviews often take over a year to complete. There are calls for the Collaboration to be capable of a rapid response under special circumstances; such a process was outlined at the Freiburg Colloquium with an indicative review completion time of 35 days. In March 2009 the Collaboration was approached by the World Health Organisation (WHO) with a rapid review topic. We tested the feasibility of rapid review. Objectives: To complete a rigorous Cochrane review within 35 days; to reflect on the rapid review process and identify associated benefits and risks. Methods: We identified a review author with immediate availability and initiated collaboration with stakeholders, relevant Cochrane groups and the WHO. Review methods were followed in accordance with the Cochrane Handbook. Results: A scoping review clarified the question. A protocol was peer reviewed by day 9. The review question was revised in consultation with the WHO after submission of protocol. We identified 457 citations, 19 were retrieved in full. Duplicate, independent screening identified no relevant trials. The draft review was peer reviewed and refined by day 35; peer reviewers responded in 48 hours (protocol) and 5 days (review). One review group coordinated the process with members of the editorial base becoming review authors. We observed how boundaries between editorial and authorship roles can blur with the potential to introduce bias. Other potential threats to the relevance and validity of this review as a direct result of its rapid nature included the risk of important review processes occurring in tandem rather than sequentially; the reduced time allowing for less reflection and consultation regarding the question and eligibility criteria. Conclusions: Rapid reviews are possible but there may be trade-offs in terms of review quality and relevance. Review Groups must develop internal processes for reducing risk of bias in rapid reviews.