The last decade has seen an increase in the use and publication of performance data about public services in the UK and elsewhere. Though there are many reasons for this increase, the need to support citizen's trust in public provision has been a commonly given reason for the implementation of performance measurement. However there is little evidence of citizens' use of, involvement with or understanding of performance measurement data. This paper contextualises trust in terms of its interrelationship between citizens and the publication of performance ratings and uses Gidden's conceptualisation of trust in abstract systems to shed light on the shifting nature of trust in the public sector. This enables us to see trust as part of a complex and changing process that gradually shifts trust from personal level to the level of trust in new knowledge. There is emerging, limited empirical evidence indicating that the declared aim of increasing trust between citizens and the public sector may be hindered or even contradicted by the ill-considered publication of performance data. To illustrate this, empirical evidence from current studies in the publication of performance ratings in the health sector is discussed. By reflecting on the concept of abstract systems a more complex trust relationship between citizens and the public announcement of performance ratings emerges.