The Clinical Trials Regulation (EU) No 536/2014 (CTR) came in force on January 31, 2022, specifying requirements for performing clinical trials in the EU and the European Economic Area (EEA). The CTR and the Clinical Trials Information System (CTIS) harmonise the approval process of clinical trials across the EU/EEA, provide a transparent process, and increase public access to information from clinical trials. Such transparency efforts must assure protection of personal data and commercially confidential information. The CTIS transparency rules were revised and recently implemented. The revised CTIS transparency rules focus on easier and earlier access by the public to documents of primary focus for patients and researchers. This article highlights the protection of personal data and commercially confidential information in public clinical trial documents according to the revised rules and also the EMA Policy 0070, which have overlapping transparency requirements. Medical writers and other functions involved in the preparation of regulatory documents during the clinical drug development play an integral role in applying transparency principles.   Medical Writing. 2024;33(3):12–21. https://doi.org/10.56012/frkj6889