Under the auspices of the UK Scientific Advisory Group on Pandemic Influenza, five scientific papers dealing with the main clinical countermeasures (antivirals, pre-pandemic and pandemic specific vaccines, antibiotics and facemasks) and the risk of a pandemic originating from an H5N1 virus were developed. These papers were reviewed and revised by additional national and international expert scientific reviewers and subsequently at a colloquium, convened by the Secretary of State for Health, of scientific experts. Revised papers were then submitted to the Scientific Advisory Group for final endorsement as reflecting an accurate and comprehensive summary of the state of knowledge in June 2007. The final endorsed papers have now been made publicly available as a resource to all. 1 Papers reviewing the scientific evidence base in the following areas are available at: http://www.advisorybodies.doh.gov.uk/ spi/evidence.htm (i) The use of antiviral drugs in a pandemic; (ii) pre-pandemic and pandemic specific influenza vaccines; (iii) the use of antibiotics for pandemic influenza; (iv) the use of face masks during a pandemic; and (v) the risk of a pandemic originating from H5N1.