Trial reference number

The identifer is an identification number that the website assigns to a trial when it is registered. The trial identifer number is in the format “NCTXXXXXXXX”. The trial is not registered until a trial identifer number is assigned.

Trial name

The official title of a clinical trial. Sometimes a trial also has a short title written in language that is easier for the public to understand.

Trial purpose

The main reason for the clinical trial. The main purpose types include treatment, prevention, diagnostic, quality of life (supportive care), screening, and others.


A clinical trial’s requirements (criteria) for people who want to join. Eligibility criteria consists of:

  • Inclusion criteria, the factors (or reasons) that allow a person to join a clinical trial.
  • Exclusion criteria, the factors (or reasons) that prevent a person from joining a clinical trial.

About the trial/trial design

The research methods and strategies used in the clinical trial.

Trial phases

The phase of the clinical trial, which is a number 1 through 4. The phase is based on the trial’s goals, the number of participants, and other characteristics.

Learn more about the 4 clinical trial phases


Trial dates

The start date is the actual date on which the first participant was enrolled in a clinical trial. The “estimated” start date is the date that the researchers think the trial will start.

Still have questions?

Understanding clinical trials is important when making the decision to join one. Our FAQ section has answers to commonly asked questions and a glossary of words to know.

Frequently asked questions