Effective health care is a relational activity, that is, it requires social relationships of trust and mutual understanding between providers and those needing and seeking care. The breakdown of these relationships is therefore impoverishing, cutting people off from a basic human capability, that of accessing of decent health care in time of need. In Tanzania as in much of Africa, health care relationships are generally also market transactions requiring out-of-pocket payment. This paper analyses the active constitution and destruction of trust within Tanzanian health care transactions, demonstrating systematic patterns both of exclusion and abuse and also of inclusion and merited trust. We triangulate evidence on charges paid and payment methods with perceptions of the trustworthiness of providers and with the socio-economic status of patients and household interviewees, distinguishing calculative, value based and personalised forms of trust. We draw on this interpretative analysis to argue that policy can support the construction of decent inclusive health care by constraining perverse market incentives that users understand to be a source of merited distrust; by assisting reputation-building and enlarging professional, managerial and public scrutiny; and by reinforcing value-based sources of trust.