Media/Press Resources


Overview is a Web-based resource that provides patients, their family members, health care professionals, researchers, and the public with easy access to information on publicly and privately supported clinical studies on a wide range of diseases and conditions. The Web site is maintained by the National Library of Medicine at the National Institutes of Health (NIH). Information on is provided and updated by the sponsor or principal investigator of the clinical study. Studies are generally submitted to the Web site (that is, registered) when they begin, and the information on the site is updated throughout the study. In some cases, results of the study are submitted after the study ends. This Web site and database of clinical studies is commonly referred to as a "registry" and "results database." includes information about medical studies in human volunteers. Most of the records in describe clinical trials (also called interventional studies). A clinical trial is a research study in which human volunteers are assigned to interventions (for example, a medical product, behavior, or procedure) based on a protocol (or plan) and are then evaluated for effects on biomedical or health outcomes. also includes records describing observational studies and programs providing access to investigational drugs outside of clinical trials (expanded access). does not contain all clinical studies conducted in the United States because not all studies are required by law to be registered, such as observational studies and trials that do not study a drug, biologic, or device (see FDAAA 801 Requirements for more information). However, the rate of registration has increased over time as more policies and laws requiring registration have been enacted and as more sponsors and investigators voluntarily register their studies. was made available to the public on February 29, 2000 and the results database was released in September 2008. Once a study is registered on the site, it is not removed. The full history of changes made to a record can be accessed by viewing the archival version of the record on the archive site.

Read a complete account of the development and expansion of in response to changes in policies and laws on the History, Policies, and Laws page.

Searching does not require registration or personal identification. Because is a government Web site, it does not host, or receive funding from, advertising or the display of commercial content. Statistics receives more than 95 million page views per month and 60,000 unique visitors daily (as of February 2012)

The following statistics are updated nightly:

  • currently contains 140,426 study records. 37,420 studies are recruiting participants. Studies are sponsored by NIH, other Federal agencies, nonprofit organizations, and private industry.
  • Studies listed in the database are conducted in all 50 States and in 182 countries.

For more statistics, charts, and maps related to, see the Trends, Charts, and Maps page.

Who Uses

The main users of the site are patients, their families and caregivers, health care professionals, clinical researchers, and study record managers.

They use to:

Clinical researchers also use the site to stay current on developments in their field of interest, find collaborators, and help identify unmet research needs. Other researchers may use the site to compile information on the research being conducted in a particular area to support the development of practice guidelines or reviews of completed research. In addition, clinical researchers or their study record managers must register their studies and submit study results to using a Web-based system called the Protocol Registration System. For more information, see:

Related Journal Publications

Awards Wins the Innovations in American Government Award

In 2004 was cited by the Ash Center for Democratic Governance and Innovation at the Harvard Kennedy School as "a successful model for the creation and maintenance of a system that processes and presents large amounts of specialized information to a wide range of users" and was selected as one of five award winners. The Innovations in American Government Awards is the nation's preeminent program devoted to recognizing and promoting excellence and creativity in the public sector. The program highlights exemplary models of government innovation and advances efforts to address the nation's most pressing public concerns.


For more information including interview requests, please contact the National Library of Medicine Office of Communications and Public Liaison Director Kathy Cravedi ( or 301.496.6308) or Deputy Director Melanie Modlin ( or 301.496.7771).

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This page last reviewed in August 2012