Introduction The potential power of public health policies emphasises the need for sound decision-making. Using research evidence to underpin public health policy has been strongly promoted; however, its implementation has not been straightforward. This study explores the use of research evidence in public health decision-making.

Methods We systematically reviewed empirical studies on the use of research evidence in public health policy (18 studies included). The identified gaps were explored through an in-depth qualitative study involving 40 interviews and three focus group discussions with senior public health decision-makers.

Results Decision-making for public health is complex. This reflects the wide determinants of health, the extensive associations between long-term conditions, and the necessity to work across sectors. A vast range of types of research evidence are used in decision-making. However, this evidence competes with many other influences. Barriers to the use of research evidence are well-described and include: decision-makers' negative perceptions of research evidence; the gulf between researchers and decision-makers; the political process of decision-making; practical time and resource constraints and limited capacity.

Ways of overcoming these barriers are less well known, and include: changing the culture of decision-making; targeting research at the needs of decision-makers; clearly highlighting key research messages; and capacity building.

Conclusion A broader conception of evidence is required to underpin public health decision-making. Achieving evidence-informed public health policy requires action by both decision-makers and researchers, in order to address the barriers identified in this study.