“The good news is that evidence can matter. The bad news is that it often does not.”1

If imitation is the sincerest form of flattery, the clinicians and clinical epidemiologists who promoted evidence-based medicine in the early 1990s should feel flattered. Evidence-based medicine now has many imitators: from evidence-based nursing,2 dentistry3 and public health4 through to evidence-based social work and social interventions.5 6 To this growing list, we can now add evidence-based global health policy, a ‘movement’ that is gaining increasing prominence.7 8

We are firm supporters of this movement. Indeed, we lead a project called the Evidence to Policy initiative (E2Pi), which aims to help narrow the gap between evidence synthesis and practical policymaking in global health. Research evidence has undoubtedly been crucial in formulating countless global health policies which have saved many millions of lives.9 Improving the flow of evidence between global health researchers and policymakers is an important tool for improving health outcomes and thus supporting low-income countries in reaching the Millennium Development Goals. For example, up to 70% of deaths of young children could be prevented through the better use of existing evidence.10

However, although evidence-based policymaking in global health has scored many successes, at the same time, we believe there are several common fallacies about its ‘real world’ application. We hope this perspective will spark discussion and debate on its payoffs and pitfalls.