ClinicalTrials.gov Trial Registry

U.S. National Library of Medicine registry and results database tracking over 440,000 human clinical studies across more than 220 countries.

Specifications & Metrics

type: Clinical Trial Registry & Results
maintainer: U.S. National Library of Medicine (NLM) at the National Institutes of Health (NIH)
identifier format: NCT<8-digit integer> (National Clinical Trial number, e.g., NCT03745287)
license: U.S. Government Public Domain work (REST API and bulk XML/JSON download)
introduced: 2000

Mandated by the Food and Drug Administration Modernization Act of 1997 (Public Law 105-115) following earlier AIDS clinical trial information efforts (1988), ClinicalTrials.gov launched publicly in February 2000 under the NIH National Library of Medicine.
Each NCT record documents study phase (Phase I–IV), interventional arms, inclusion/exclusion eligibility criteria, primary and secondary clinical endpoints, enrollment size, and study sponsor.
The FDA Amendments Act of 2007 (FDAAA 801) and International Committee of Medical Journal Editors (ICMJE) policies require prospective trial registration and mandatory summary results reporting (including serious adverse events).