How to Use Advanced Search


How to Use the Advanced Search Form

The Advanced Search form lets you focus your search, giving you more control over the results. You can access the advanced search form by:

  • Clicking on the Advanced Search link found on the home page and at the top of every page under the search box
  • Choosing Advanced Search from the Find Studies menu
  • Clicking on Modify this search at the top of any Search Results list (see How to Modify a Search)

You can use the multiple search fields on the advanced search form to narrow or broaden your results. For example, you can specify the condition, recruitment status, age group of participants, and location where studies are conducted. See the Advanced Search Field Definitions for a complete list of options.

  • Enter your search terms in one or more fields and click on Search.
  • A list of search results will be displayed. The total number of studies found is shown at the top, along with your search terms.
  • The first column of the search results list, Rank, indicates the order in which the studies are listed. Studies that most closely match your search terms are listed first. The Status column shows which studies are open, or recruiting new volunteers, and which studies are closed, or not recruiting new volunteers.


  • You do not need to fill in all the search fields. Complete only the fields that are needed for your search.
  • To do a basic search using the Advanced Search form, fill in the first field, labeled Search Terms.
  • Click on a field label, such as Recruitment, to learn more about that field.
  • Try using operators such as AND, OR, and NOT to broaden or narrow your search.
  • If your search results do not include enough studies, consider clearing one or more search fields on the form and trying the search again.

Practice some sample searches:

Open Studies | Interventional Studies | melanoma
Aspirin | United States, New York | Studies with Male Participants
lung tumor | Studies With Results

Advanced Search Fields

The following search fields are available on the Advanced Search page. They are listed in the order in which they appear on the form. To view information on a search field, click on its name below. You can also click on the field label on the advanced search form to bring up a window containing information for that field.

Information and instructions for all fields are provided on the Advanced Search Field Definitions page.

Search Term Highlighting

The words you type in the Advanced Search Form fields will be highlighted in the text of each of the study records found by your search. Search words will be highlighted in pink, and synonyms for search words will be highlighted in yellow. For example, if your search words are heart attack, the words heart and attack will be highlighted in pink wherever they appear in each record. Synonyms for heart attack, such as myocardial infarction, will be highlighted in yellow.

Highlighted search term and synonym

Searches Using the Operators AND, OR, and NOT

Words such as AND, OR, and NOT (in all uppercase letters), called "operators," tell the search function how the words in your search relate to each other.

  • Use AND to find study records that contain all the words connected by AND.

    Example: prostate cancer AND radiation

    This search finds study records that contain information on both prostate cancer and radiation. Using AND narrows your search.

  • Use OR to find study records that contain either word connected by OR.

    Example: aspirin OR ibuprofen

    This search finds study records containing either the word "aspirin" or the word "ibuprofen." Using OR broadens your search.

  • Use NOT to find study records that do not contain the word following NOT.

    Example: immunodeficiency NOT AIDS

    This search finds study records containing the word "immunodeficiency" but excludes records containing the word "AIDS" from the search results.

  • Use AND, OR, NOT, and parentheses to create more complicated search expressions.

    Use parentheses in searches that contain more than one operator (AND, OR, NOT). This means that the words that are together in parentheses will be treated as a unit.

    Example: (heart disease OR heart attack) AND (stroke OR clot)

    This search finds study records containing either the phrase "heart disease" or "heart attack" as well as records containing either the word "stroke" or the word "clot."

  • Using AND and OR as operators can sometimes be confusing.

    The correct way to search for a phrase such as:

    Ear, Nose, and Throat Conditions

    is to enter:

    (Ear OR Nose OR Throat) AND Conditions

    However, the search will still recognize the phrase "Ear, Nose, and Throat."

  • To search for and as a word, instead of using it as an operator, put it in quotation marks.

    You can search for or, not, and parentheses in the same way.

Learn More

This page last reviewed in August 2012