Please note that the Ontario Health Study website and questionnaire will be unavailable due to routine maintenance from 8am on Saturday, December 17th to 10pm Sunday, December 18th. We apologize for the inconvenience.

Join the fight against cancer and chronic disease!

The Ontario Health Study (OHS) is a long-term Health study following the health of more than 230,000 Ontarians collecting data through questionnaires, blood samples and physical measurements. The goal is to build a platform that researchers can use now and decades into the future to better understand the causes of cancer and chronic disease.

Find out more


Discovery—It's in your blood.

Provide a blood sample to the Ontario Health Study.

Click here to learn more.

Tell us how you're doing.

Update us on your health by filling out our first follow-up questionnaire.

Click here to learn more.


Is the OHS coming to your community?

There are not currently any Local Study Centres available. Please check back soon as more locations will be announced soon. If you have an Ontario Health Study account and are eligible to visit a Local Study Centre, you will automatically receive an invitation when a location is announced near you.