Transforming the UK's clinical trial landscape
The UK's clinical trial regulations are changing.
The Health Research Authority (HRA) has been working in partnership with the Medicines and Healthcare products Regulatory Agency (MHRA) to amend the Medicines for Human Use (Clinical Trials) Regulations 2004.
Our goal is to create a modern, streamlined regulatory environment that maintains high standards of participant safety while accelerating access to innovative treatments.
Feedback from a public consultation in 2022 helped shape proposals to improve how clinical trials of medicinal products (CTIMPs) are run in the UK. These changes aim to make the UK one of the best places in the world to conduct clinical research.
The updated Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025 have now been approved.
This page brings together everything you need to know during the implementation period and beyond.
New guidance to support researchers and sponsors
We've published new guidance to accompany the updated clinical trials regulations.
Who these changes affect
These updated regulations will impact everyone involved in CTIMPs in the UK:
- researchers and sponsors
- Research Ethics Committees (RECs)
- trial participants and the public
- healthcare professionals
Why these changes matter
The reforms will:
- align the process for the MHRA and RECs to review and approve applications and substantial modifications
- enhance transparency and accountability for research findings
- reduce unnecessary burdens while upholding ethical and safety standards
Together, these improvements will strengthen the UK's position as a global leader in clinical research.
Key changes in the regulations
The following areas of the regulations have been updated.
Transparency
For the first time, it will be a legal requirement to:
- register clinical trials in a public registry
- publish a summary of trial results within 12 months of completion
- offer to share a summary of results with participants (or their representative) in a format they can easily understand
Provisions for deferrals in specific circumstances, such as phase I trials involving healthy volunteers, will be available. We'll provide guidance to support researchers in meeting these new requirements.
Research Ethics Committees (RECs)
Changes to RECs will improve flexibility while aligning with international good clinical practice (ICH-GCP E6). When the new regulations come into force RECs will:
- need at least five members that collectively possess the qualifications and experience to review and evaluate any proposed trials' scientific, medical, and ethical aspects
- still be expected to have an appointed Chair
- include one lay member
Guidance instead of legislation
Some areas will be supported through detailed guidance rather than new legal requirements.
We are leading work on guidance to support best practices in diversity and inclusion, and public involvement in clinical trials.
Diversity and inclusion in clinical trials
Including a wider range of participants ensures trial findings reflect the entire population's needs.
Our Public Perceptions of Research - Health Research Authority found that:
- 88% believe trials should involve a diverse group of participants.
- 70% support this even if it increases costs
- 74% are in favour even if it extends timelines
We've developed a draft set of questions and supporting guidance jointly with the Medicines and Healthcare products Regulatory Agency (MHRA) for researchers to consider when they design clinical trials and clinical investigations. The answers to these questions will form the basis of an Inclusion and Diversity Plan.
This will help ensure clinical research is designed to include people who could be impacted by the findings, and that people underserved by research are not overlooked.
Following an informal consultation on the draft questions and supporting guidance in 2024, we are undertaking a pilot in which sponsors and researchers will be invited to submit a plan as part of their IRAS application. If you are planning to submit an application for a clinical trial or clinical investigation in 2025 and would be interested in taking part, please get in contact.
Public involvement
Involving the public in designing, delivering, and reporting clinical trials leads to better outcomes and builds trust.
We're updating our website to:
- provide clear expectations for public involvement in health and social care research, including all phases of clinical trials
- point to the wide range of resources available across the sector
- include specific recommendations for Phase 1 healthy volunteer trials
The updates will help researchers meaningfully involve the public in all clinical trials.
Timeline of key changes

Past milestones
- March to April 2022 - public consultation
- December 2024 - Statutory Instrument laid before Parliament
- February 2025 - approved by Westminster Parliament and House of Lords
- April 2025 - approval from the Northern Ireland Assembly and final ministerial sign off
- June 2025 - new guidance is published to accompany the new regulations
What's next
- 28 April 2026 - implementation of the amended regulations
Post-publication note
The new clinical trials regulations will now come into force on 28 April 2026.
The date was changed due to a technical issue during the final processing of the Statutory Instrument (SI) within the digital legislation platform, which meant the SI needed to be re-signed on 28 April 2025.
Support for researchers and sponsors
We're working closely with our stakeholders to ensure there is a smooth transition for the updated regulations.
To help with this we'll be producing:
- guidance – new resources will be published throughout 2025 (see guidance section below)
- training – online sessions, webinars and workshops will be available to explain the changes
- frequently asked questions – answers to common questions will be hosted on this page
New guidance to accompany clinical trials regulations
We’ve now published guidance to help prepare researchers and sponsors for the changes that will happen when the new clinical trials regulations come into force in April 2026.
The guidance outlines the review and assessment processes for CTIMPs by RECs and the MHRA.
Our guidance covers the following updates to the regulations which have been a key focus for the HRA:
- definitions and terminology
- pharmacovigilance
- the approvals process for clinical trials
- Research Ethics Committees that review clinical trials
- simplified arrangements for consent in clinical trials
- research transparency requirements for clinical trials
The guidance does not cover changes to other reviews of CTIMPs, for example study wide review. If changes are made to the way we review these types of applications or to non-CTIMP applications, we’ll share separate guidance and information with you.
If you have any comments or would like to share feedback on the new published guidance, please complete our online survey by 5pm on Wednesday 10 September 2025.
If you would prefer to provide your feedback on how our guidance is written by email, or you have any questions, please email the HRA's engagement team.
The MHRA has also published separate guidance to accompany the new regulations which you can read on their clinical trials hub.
Useful links
- MHRA – Clinical Trials Regulation
- NIHR – Supporting Research in the UK
- EU Clinical Trials Regulation (CTR)
Sign up for updates on the clinical trial regulations
We send out regular email updates on the changes to the clinical trials regulations in the UK.
These emails included updates on the different areas the HRA is leading on, as well as opportunities to get involved and provide feedback.
You can take a look back at previous editions on our clinical trials update webpage.