What is a clinical trial?

Clinical trials are an important part of developing new medical and other interventions that may improve the health and wellbeing of all Australians. Find out what a clinical trial is, why they’re important, and the different types and phases of clinical trials.

About clinical trials

Many clinical trials allow researchers to try out new treatments, tests or procedures that may prevent, detect or diagnose, treat or manage diseases or conditions. We will refer to these treatments, tests or procedures as interventions.

You can volunteer to take part in a clinical trial.

Some trials look at how people respond to a new intervention and what side effects might occur. This helps to determine if a new intervention works, is safe, and is better than those already available.

Researchers also use clinical trials to:

  • compare existing interventions
  • test new ways to use or combine existing interventions
  • test new ways to deliver therapies and other care
  • observe how people respond to other factors, such as dietary changes.

Clinical trials study a range of interventions, including:

  • pharmaceutical interventions: experimental drugs, cells and other biological products, vaccines
  • disease detection and treatment methods: new ways to detect and treat disease, diagnostic or screening tests
  • therapeutic strategies: psychotherapeutic and behavioural therapies
  • medical or surgical procedures and devices
  • health-related service changes
  • preventive care and educational interventions.

Why we need clinical trials

Clinical trials are essential to the development of new interventions that help people to live longer and to have less pain or disability.

Computer simulation and animal testing can only tell us so much about how a new treatment might work. Testing on a living human body helps determine if:

  • new medicines developed in the laboratory using animal models, human tissue samples or cells are effective or safe
  • a diagnostic test works properly in a clinical setting.

Testing on a large number of people ensures that results are broadly consistent and not just for one person or a small group of people.

New treatments for diseases and conditions including cancer, heart disease, high blood pressure and asthma, have been developed through clinical research.

Clinical trials can also help to raise standards of treatment. International researchers recognise the high quality of patient care in Australian clinical trials.

Learn more about the potential benefits and risks of taking part in a clinical trial.

Types of clinical trials

Treatment trials

Treatment trials test:

  • new treatments
  • new medicines or combinations of medicines
  • new medical devices
  • new approaches to surgery
  • other new medical and non-medical therapies.

Diagnostic or screening trials

Diagnostic or screening trials evaluate tests or procedures to diagnose and detect diseases or conditions.

Prevention trials

Prevention trials test new ways to prevent disease, including medicines, vaccines, vitamins, or changes to diet, lifestyle or behaviour.

Phases of clinical trials

Clinical trials are often conducted in phases, starting with a small number of participants and then increasing the number. Clinical trials of biomedical interventions usually have 4 phases.

Phase 1

Phase 1 clinical trials:

  • test a new intervention for the first time
  • use a small number of people (between 20 and 80)
  • determine a safe dosage range
  • identify side effects.

Phase 2

Phase 2 clinical trials:

  • use a larger group of people, for example several hundred
  • determine efficacy; that is, whether it works as intended
  • further evaluate safety.

Phase 3

Phase 3 clinical trials:

  • use large groups of people, from several hundred to several thousand
  • compare the intervention to other standard interventions, experimental interventions, standard care or a placebo
  • monitor adverse effects
  • collect information that will allow the intervention to be used safely.

Phase 4

Phase 4 clinical trials:

  • happen after an intervention is in use
  • monitor the effectiveness of the approved intervention in the general population
  • collect information about any adverse effects associated with widespread use over longer periods of time
  • may also be used to investigate potential use of the intervention in a different condition, or in combination with other therapies.

Other phases

Exploratory studies

Exploratory studies are sometimes referred to as ‘Phase 0 trials’ or ‘pilot studies’. They come before Phase 1 trials and test how the body responds to an experimental drug. This type of trial uses a very limited number of people and involves small doses of the new drug, given once, or for a short time.

Clinical trials of diagnostic tests

To see how effective and how accurate diagnostic tests are, trials are sometimes divided into exploratory phases, challenge phases and advanced phases.

Funding for clinical trials

Various organisations or individuals sponsor or fund clinical trials, including:

  • government departments and agencies
  • research groups
  • foundations
  • charities
  • pharmaceutical, medical device and biotechnology companies.

Funding information

We do not run or manage clinical trials. Information about funding schemes is available on the following websites:

Sponsors seeking further advice on conducting clinical trials in Australia should contact the Therapeutic Goods Administration.


Date last updated:
  • About clinical trials