Definition · Plain-language
ClinicalTrials.gov
ClinicalTrials.gov is the public registry and results database of clinical studies maintained by the US National Institutes of Health through the National Library of Medicine.
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What ClinicalTrials.gov is
ClinicalTrials.gov is a web-based resource that provides public access to information on clinical studies of human participants conducted around the world. Maintained by the National Library of Medicine at the National Institutes of Health, it functions both as a registry — recording a study’s design, eligibility criteria, sponsor, locations and status before or during conduct — and as a results database that holds summary outcome and adverse-event information after a study finishes. It is one of the largest trial registries and a widely used reference for the research community.
Why registration matters
Prospective registration of trials supports transparency and helps counter publication bias by creating a public record of what was planned, regardless of whether results are later published in a journal. It allows patients and clinicians to find studies, enables systematic reviewers to identify all relevant trials, and lets the public see what outcomes were measured. Many journals and ethics bodies expect registration in a recognised registry as a condition of conduct or publication, reinforcing its role as an integrity safeguard.
The FDAAA 801 legal requirement
In the United States, registration and results submission are not merely encouraged but legally mandated for certain studies. The Food and Drug Administration Amendments Act of 2007, section 801 (FDAAA 801), and its implementing regulation require responsible parties for "applicable clinical trials" — broadly, many controlled trials of drugs, biologics and devices — to register the trial and submit summary results to ClinicalTrials.gov within defined timeframes. Failure to comply can carry penalties. The legal scope is specific, so not every study falls within the mandate.
Key facts
At a glance
- Definition: US public registry and results database of clinical studies.
- Maintained by: NIH National Library of Medicine (NLM).
- Functions: Study registry plus a summary-results database.
- Legal basis: FDAAA 801 (2007) and its implementing regulation.
- Applies to: Responsible parties for "applicable clinical trials".
- Purpose: Transparency and reduced publication bias.
Common misconceptions
What people often get wrong
Often heard: ClinicalTrials.gov only lists trials conducted in the United States.
Actually: It includes studies conducted worldwide. While the FDAAA 801 legal mandate is US-based, the registry itself records trials from many countries.
Often heard: Every clinical study must by law be registered on ClinicalTrials.gov.
Actually: The legal requirement under FDAAA 801 applies to defined "applicable clinical trials". Many studies register voluntarily or to meet journal and ethics expectations, but the statutory mandate is specific in scope.
Often heard: A listing on ClinicalTrials.gov means the trial’s treatment is FDA-approved.
Actually: Registration only records that a study exists and its details; it implies nothing about approval or effectiveness of any intervention studied.
Going deeper
