Health systems are inherently relational and so many of the most critical challenges for health systems are relationship and behaviour problems. Yet the disciplinary perspectives that underlie traditional health policy analysis offer only limited and partial insights into human behaviour and relationships. The health sector, therefore, has much to learn from the wider literature on behaviour and the factors that influence it. A central feature of recent debates, particularly, but not only, in relation to social capital, is trust and its role in facilitating collective action, that is co-operation among people to achieve common goals. The particular significance of trust is that it offers an alternative approach to the economic individualism that has driven public policy analysis in recent decades. This paper considers what the debates on trust have to offer health policy analysis by exploring the meaning, bases and outcomes of trust, and its relevance to health systems. It, first, presents a synthesis of theoretical perspectives on the notion of trust. Second, it argues both that trust underpins the co-operation within health systems that is necessary to health production, and that a trust-based health system can make an important contribution to building value in society. Finally, five conclusions are drawn for an approach to health policy analysis that takes trust seriously.