Medical writers maintain a fine balance between data transparency obligations and personal data protection in clinical reports. Hence, we must stay informed of data protection requirements outlined in the EU General Data Protection Regulation (GDPR) 2016/679 and their interaction with data transparency requirements of the EU Clinical Trials Regulation (EU-CTR) 536/2014 and EMA Policy 0070. Medical writers need to understand the core concept of personal data versus anonymised data and the differences between working for a data controller versus working for a data processor. This article explores how a clinical research organisation, as the data processor, assists client companies, as the data controller, fulfil transparency obligations, illustrated by a successful collaboration model. We examine how medical writers contribute to an organisation’s disclosure-readiness as well as promote the value of a disclosure-informed medical writer’s upstream impact as clinical reports anonymisation specialists throughout the clinical trial lifecycle. Medical Writing. 2024;33(4):64–67. https://doi.org/10.56012/vmom7031