The Open Planets Foundation (OPF) has suggested the need for digital preservation repositories to perform periodic “health checks” as a routine part of their preservation activities. In the same way that doctors monitor basic health properties of their patients to spot indications of infirmity, repositories should monitor a set of properties associated with “preservation health” to provide an early warning of potential threats to the ongoing security of the archived digital objects in their care. The Preservation Health Check (PHC) project, undertaken as a joint effort by OPF and OCLC Research, aims to evaluate the usefulness of the preservation metadata created and maintained by operational repositories for assessing basic preservation properties. The PHC project seeks to develop an implementable logic to support preservation health checks of this kind, and to test this logic against the store of preservation metadata maintained by an operational preservation repository. The Bibliothèque Nationale de France has agreed to share their preservation metadata in support of this project. The authors aim is to advance the use of preservation metadata as an evidence base for conducting preservation health checks according to a standardized, widely-applicable protocol. Doing so opens up possibilities for internal or third-party threat assessment services …