The Voice of EHDEN podcast is pleased to continue our occasional ELSI series, and this is the first episode of season 4, focusing on the concept of 'trust' within the context of health and health research, and in particular real world data. In this episode we are joined by Dr Mackenzie Graham, Senior Research Fellow in Data Ethics, Wellcome Centre for Ethics and Humanities, University of Oxford. Mackenzie has a facinating background in neuroscience, data and data ethics, and also collaborates with Dr Mark Sheehan and Dr Richard Milne, our participants in the first episode of our ELSI series. In the discussion, we explore what is meant by, 'trust', and also trustworthiness, and reliance on appropriate governance systems to support individuals and patients being confident in who and how they can trust. Within this we investigate underlying concepts that result in trust, what it is and what it takes for trust and trustworthiness, such as motives and prior experience, very much within a motivation-based model. Beyond this, we focus in on aspects of data use, the role of Tech Titans and trade offs we all make in society around the use of our personal data, through to sociotechnical architectures, e.g., Trusted Research Environments (TREs), federated data networks, like EHDEN, DARWIN EU(R) and the European Health Data Space (EHDS). From this the attributes, roles and actor's responsibilities are articulated, and a delineation of both passive and active activity around trust. Finally, we land on the counter factual concept of 'distrust' and the need to explore this further, especially in the context of health and health data use for research. Specifically the role of TREs is explored in terms of trust, and Mackenzie and colleagues recently published in the Journal of Medical Ethics on, 'Trust and the Goldacre Review: why trusted research environments are not about trust', available here, and speaking to a number of aspects discussed in this episode. The views expressed by the participants are personal and not necessarily reflective of their organisations.