There is general optimism and enthusiasm that the introduction of Big Data and related technologies will substantially change and improve delivery of medical care and healthcare decision making. In the project proposed here we will explore how the use of routinely collected data (RCD) can be of real benefit for healthcare decision-making. To achieve this objective, we will explore the technical, legal and ethical problems related to collecting and aggregating data, data quality, and assess how and to what extent these data can be turned into evidence. Subsequently, we will examine the prospects of relying on RCD in the market authorisation and surveillance of pharmaceuticals and medical devices. Afterwards, the use of algorithm-based decision-making and their impact on ethical and legal issues related to transparency, accountability and liability will be assessed. Based on these findings, we will investigate how the evidence resulting from RCD can be further integrated into transparent and comprehensible clinical decision-making by healthcare professionals and patients. In this project, retrospective analyses will be conducted on the M@tric database and novel data will be collected (and processed) from physicians in an in-depth interview study and a survey study.