The National Library of Medicine (NLM), a division of the National Institutes of Health (NIH), is the agency responsible for developing and maintaining ClinicalTrials.gov, the world’s largest clinical trials database. The site currently lists over 573,000 studies conducted across all 50 states and 225 countries.
How ClinicalTrials.gov Was Created
The database exists because Congress required it. The Food and Drug Administration Modernization Act of 1997 (FDAMA) was the first U.S. federal law to require clinical trial registration. Section 113 of that law directed the NIH to build a public information resource covering certain clinical trials regulated by the FDA. ClinicalTrials.gov launched in 2000 as a free, publicly searchable website.
A decade later, Congress significantly expanded the database’s scope. The Food and Drug Administration Amendments Act of 2007 (FDAAA) added a requirement that trial sponsors not only register their studies but also report results. This turned ClinicalTrials.gov from a simple registry into a registry and results database. Under the 2007 law, results must be submitted in a standardized format covering participant demographics, outcomes for primary and secondary endpoints, statistical analyses, and adverse events. Sponsors must also upload the full study protocol.
Who Submits Data to the Database
Every covered clinical trial has a “responsible party” who is legally obligated to register the trial and later submit results. That person is either the trial’s sponsor (often a pharmaceutical company, university, or government agency) or the principal investigator, if the sponsor formally designates them. To qualify as the responsible party, a principal investigator must have control over the trial data, the right to publish results, and the ability to meet all federal submission requirements.
This means the NIH builds and runs the platform, but the actual data flowing into it comes from thousands of individual sponsors and researchers around the world.
What Happens When Sponsors Don’t Comply
The FDA handles enforcement. If a responsible party fails to register a trial or submit results on time, the FDA can issue a pre-notice letter flagging the potential violation. If the problem isn’t corrected, the FDA escalates to a formal Notice of Noncompliance. Responsible parties that still don’t take corrective action within 30 days of that notice face civil money penalties. In serious cases, the FDA can pursue injunctions or criminal prosecution.
The NLM’s Role Today
The National Library of Medicine doesn’t just host the database. It actively develops and improves the platform. Starting in 2019, NLM undertook a multi-year modernization project to overhaul both the public-facing website and the behind-the-scenes system researchers use to submit data (called the Protocol Registration and Results System, or PRS). The modernized version of ClinicalTrials.gov became the sole website in June 2024, replacing the older “classic” interface. Updates to the submission system continued through 2025, adding features like field-level error checking that helps researchers fix problems in their submissions before they’re finalized.
How It Fits Into Global Trial Registration
ClinicalTrials.gov is one of several national registries that feed into a broader international system. The World Health Organization runs the International Clinical Trials Registry Platform (ICTRP), which aggregates data from registries worldwide. ClinicalTrials.gov is a primary registry in the ICTRP network, meaning its data meets WHO standards for trial transparency and is searchable through the WHO’s global portal. For researchers and patients outside the U.S., this connection makes American trial data accessible alongside studies registered in Europe, Asia, and elsewhere.
While many countries maintain their own registries, ClinicalTrials.gov remains the largest single database by a wide margin, with its 573,000-plus registered studies dwarfing most national alternatives.