Thousands of people volunteer to take part in clinical trials every year.

Our medical advances can only happen through the efforts of many people, especially the patients who volunteer for clinical trials. When considering a clinical trial, it may help to understand the process of participation to know what to expect. We want to help you, your family, and your doctor make the right decision for you.


In prescreening, the team will check your health. If needed, they will run tests to find out if you meet the eligibility criteria listed in the protocol. The protocol is a written plan of a clinical trial, including the goals, design, and how it will answer the questions of the trial’s purpose. The team will also review with you the instructions for taking part in the trial.

Informed consent

Informed consent is the process in which researchers talk with people who are thinking about enrolling, or have enrolled, in a clinical trial. You will need to read an informed consent form (ICF) that describes the possible benefits and risks of taking part. It tells you that taking part in the trial is voluntary, and that you may leave the trial at any time.

The goal of the informed consent process is to protect the participants who enroll in clinical trials. The informed consent process starts when a possible participant first asks for information about a trial and continues until the trial ends.

Though an ICF covers most of the information you need to know to take part, it may not cover some questions about how the clinical trial may affect your everyday life. Visit our What to consider section for a list of questions to ask your trial team.


Once you have signed the ICF, the trial team will review your medical history, do physical exams, run tests (if needed), and decide if you qualify for the clinical trial. If the trial requires you to pause taking certain medicines, you would need to do so before starting the investigational treatment.

Study participation

What happens during trial participation depends on the type of trial. The trial team will tell you what will happen during participation and will answer any questions you have. You may need to do things such as:

  • Attend phone or in-person doctor visits (these could be days, weeks or months apart)
  • Write in a diary or eDiary (electronic diary)
  • Fill out surveys
  • Have tests such as blood tests, X-rays, or others
  • Give samples, such as urine or blood


Once the trial is complete, the trial team may require follow-up phone calls or visits to check on your health and write down any changes that may have happened. The trial team will tell you before you join the trial if you will need to do any follow-up.

Your safety is most important

It is important participants feel comfortable when taking part in a clinical trial. You can choose to leave a trial at any time, for any reason. It will not affect your medical care.