Cochrane reviews provide standardised and regularly updated syntheses of evidence on the effects of healthcare interventions. We present the rationale for, and some of the results of, a Cochrane review of the effects of amantadine and rimantadine in the prevention and treatment of influenza. The estimates of effect will be incorporated into a decision-making model for tackling influenza in healthy adults (i.e. soldiers in the British Army). Our systematic review of the economics of influenza also provides the international context within which economic data can be interpreted and assessed as a preliminary to an economic evaluation comparing alternative prevention and treatment strategies. Systematic reviews provide powerful and relatively inexpensive evidence of effects and tolerability, which is more likely to convince decision-makers than evidence from single studies. Additionally, they can be used to focus clinical trial questions and provide strategic insight regarding the state-of-the-art knowledge of effects and economics of compounds in a specific field.