Every Ontario resident is entitled to free access to emergency and preventive medical care under OHIP. Ontario residents may go to a participating doctor - essentially every doctor practicing in the province - any time they wish and the services are billed through OHIP to the government. It does not cover such areas as prescription drugs or dental care, but did cover one eye examination every 2 years and limited chiropractic and physiotherapy services, until most eye exams and all chiropractic and physiotherapy were "delisted," or removed from coverage, by the Liberal government of Dalton McGuinty in May 2004. OHIP is funded by taxes paid by the residents of Ontario and by transfer payments from the federal government.

In order to be eligible for OHIP, a person must be a Canadian citizen or have immigration status as set out in Ontario's Health Insurance Act, make his or her permanent and principal home in Ontario, and be physically present in Ontario 153 days in any 12-month period. There are however several exceptions to this rule.