BACKGROUND: Growing attention is being paid to the importance of trust, and its corollaries such as mistrust and distrust, in health service and the central place they have in assessments of quality of care. Although initially focussing on doctor-patient relationships, more recent literature has broadened its remit to include trust held in more abstract entities, such as organisations and institutions. There has consequently been growing interest to develop rigorous and universal measures of trust. METHODS: Drawing on illustrative ethnographic material from observational research in a UK diabetes clinic, this paper supports an approach that foregrounds social practice and resists conceiving trust as solely a psychological state that can be divorced from its context. Beyond exploring the less-than-conscious nature of trust, the interpretations attend to the extent to which trust practices are distributed across a range of actors. RESULTS: Data from clinical encounters reveal the extent to which matters of trust can emerge from the relationships between people, and sometimes people and things, as a result of a wide range of pragmatic concerns, and hence can usefully be conceived of as an extended property of a situation rather than a person. Trust is rarely explicitly articulated, but remains a subtle feature of experience that is frequently ineffable. CONCLUSIONS: A practice approach highlights some of the problems with adopting a general psychological or intellectualist conception of trust. In particular, assuming it is a sufficiently stable internal state that can be stored or measured not only transforms a diffuse and often ephemeral quality into a durable thing, but ultimately presents it as a generic state that has meaning independent of the specific relationships and context that achieve it. Emphasising the context-specific nature of trust practices does not dismiss the potential of matters of trust, when they emerge, to be transposed to other contexts. But it does highlight how, on each occasion, trust as a relational quality is ways 'done' or 'achieved' anew.