Linking to ClinicalTrials.gov

The National Library of Medicine invites you to link from your web site to ClinicalTrials.gov.

If you link to this site, provide proper attribution to the U.S. National Library of Medicine (NLM) and ClinicalTrials.gov. It must be clear to users that data and searches are being provided by ClinicalTrials.gov. Use only real-time data provided directly by ClinicalTrials.gov to ensure that the most up-to-date and accurate information is provided to the public.

Text Links

The text shown below should assist you in coding your html link to us. Paste the block of HTML code provided below directly into your page. Please observe the form of the ClinicalTrials.gov name, which should always include an uppercase C and T, a lowercase g, no space between "Clinical" and "Trials."

This HTML:

<a href="http://clinicaltrials.gov/" title="Information on Clinical Trials and Human Research Studies">ClinicalTrials.gov</a> provides patients, family members, and members of the public easy and free access toinformation on clinical studies for a wide range of diseases and conditions.

Displays this text in a browser:

ClinicalTrials.gov provides patients, family members, and members of the public easy and free access to information on clinical studies for a wide range of diseases and conditions.

Formulating Search Requests

Links to individual search fields can be constructed, as shown below. For any multiword search terms (e.g. alzheimer disease), spaces must be replaced with a "+" character. Unusual characters must be URL encoded.

Examples

Searching for Alzheimer disease studies in ClinicalTrials.gov

http://clinicaltrials.gov/search/term=alzheimer+disease

Linking to diabetes studies in ClinicalTrials.gov

<a href="http://clinicaltrials.gov/search/condition=diabetes">Diabetes studies in ClinicalTrials.gov</a>

For a multiword term that should be treated as a phrase, the spaces must be replaced with "+" characters and the entire phrase enclosed in quotes, which are URL encoded as %22. For example,

Linking to lyme disease studies in ClinicalTrials.gov

<a href="http://clinicaltrials.gov/search/condition=%22lyme+disease%22">lyme disease studies in ClinicalTrials.gov</a>

Linking to fluoxetine studies in ClinicalTrials.gov

<a href="http://clinicaltrials.gov/search/intervention=fluoxetine">fluoxetine studies in ClinicalTrials.gov</a>

Linking to clinical studies sponsored by NHLBI in ClinicalTrials.gov

<a href="http://clinicaltrials.gov/search/sponsor=NHLBI">Clinical studies sponsored by NHLBI in ClinicalTrials.gov</a>

You may show a specific study protocol record based on NCT number. The NCT number is NLM's unique identifier for a particular record and is found at the end of each record.

http://clinicaltrials.gov/show/NCT00004451

XML Format

ClinicalTrials.gov provides data in XML format as shown below. Please note that use of ClinicalTrials.gov data is subject to our Terms and Conditions.

The search results list can be obtained in XML format by appending a URL parameter, "displayxml=true", to the end of a search request URL.

Example: http://clinicaltrials.gov/search/term=%22lyme+disease%22?displayxml=true

By default, this option will return the first 20 search results. A parameter, "count=100", can be used to get the first 100 results. Another parameter, "start=101", can be used to get subsequent sets of studies.

In the following example, all three parameters are used to get results 1201-1400 out of more than 16,000 results found by a search of "cancer".

Example: http://clinicaltrials.gov/search/term=%22cancer%22?displayxml=true&count=200&start=1201

Caution: The XML for all studies is about 100 MB in size. If you attempt to display this much XML in your browser, your browser will probably freeze for several minutes and then crash.
An individual protocol record can be obtained in XML format by appending a URL parameter, "displayxml=true", to the end of a study display URL.

Example: http://clinicaltrials.gov/show/NCT00001372?displayxml=true

The structure of protocol records is defined by this Document Type Definition (DTD).
A zip file containing a set of protocol records in XML format can be downloaded by appending a URL parameter "studyxml=true" to the end of search request URL.

Example: http://clinicaltrials.gov/search/term=%22lyme+disease%22?studyxml=true

Note that downloads of many studies can take several minutes.

Crawlers

ClinicalTrials.gov makes it easy for web crawlers to find all studies. Each time the study collection is updated, pages of links to all studies are generated.

Links to all studies

Most users will not find these pages useful.

Background Information