Ontario University Athletics (OUA; French: Sports universitaires de l'Ontario) is a regional membership association for Canadian universities which assists in co-ordinating competition between their university level athletic programs and providing contact information, schedules, results, and releases about those programs and events to the public and the media.

In 1968, the O-QAA was divided into Eastern and Western Divisions in order to facilitate the scheduling of events.

In October 1975, the Canadian Interuniversity Athletics Union (CIAU) suspended the Windsor Lancers from all sports for two years, for the use of an ineligible men's football player.

Some older universities in the OUAA suggested withdrawing from the CIAU, which had different player eligibility rules.

Bob Barney of the University of Western Ontario, felt that the CIAU made a "play for real power over athletics in this country".

[1] In May 1976, the Windsor Star reported that Barney proposed realignment of schools at the 1976 OUAA general meeting, which "would bring together universities with similar philosophies towards athletics".

In 1987, the OUAA awarded playing privileges in hockey to three Quebec schools, McGill, Concordia and Trois Rivieres.

Both the OUAA and the OWIAA amalgamated to form one association, Ontario University Athletics.

In January 2006, the OUA welcomed its 19th member to the fold as UOIT was granted membership in an unanimous vote by the league's Board of Directors.

The Oshawa-based school began competition in the 2006–07 season, participating in rowing and tennis, while joining men's and women's hockey in 2007–08.

Winners of OUA championships generally go on to compete in the national U Sports competition, against the champions of the other three conferences.

These maximum capacities can and often do include standing room patrons and attendees seated on grass surrounding a playing field.