Background: Effectiveness research is highly valued within the evidence-based movement. However there has been little research to explore whether this priority is equally valued in low income countries, despite increased efforts to encourage the use of research in decision-making. Objectives: This study aimed to explore perceptions of the usefulness of research for public health decision-making in Ghana. It aimed to understand the perceived value of research and to identify the types of research considered useful for decision-making. Methods: Semi-structured interviews were conducted with 69 researchers, decision-makers and other stakeholders working in the field of public health in Ghana. Results: The concept of research was broad, incorporating routine data, government reports and even informal conversations and observations. Research was dichotomised into ‘big’, formal, academic research and ‘small’, applied research such as operations research. So-called ‘small research’ was highly valued, due to its speedy completion and its focus on topics pertinent to service delivery; big research was not always considered necessary. Effectiveness research, one type of ‘big research’, was not highly valued with regards to complex public health interventions and policies. Interviewees tended to feel that ‘effective’ policies and programmes could be designed once there was a thorough understanding of the situation. There was an implicit assumption that as long as these interventions were implemented well, they would be effective and so evaluations were not necessary. Conclusions: The lack of emphasis on evaluation and the broad definitions of research in Ghana may impede the applicability of the concept of evidence-informed decision-making. Those hoping to encourage research use in low income countries such as Ghana should be aware of, and open a dialogue about, the possible differences in perceptions and values and what they mean for efforts to support evidence-informed decision-making.