The Ontario Junior B Lacrosse League (OJBLL) is a box lacrosse league sanctioned by the Ontario Lacrosse Association in Canada. The league features twenty-four teams in Ontario, one in Quebec, and one in the Akwesasne (which straddles the two aforementioned provinces and New York) that annually play a 20-game schedule and four rounds of playoffs for the J. A. MacDonald Trophy. After the conclusion of the playoffs, a league champion represents the OJBLL at the Founders Cup National Junior B Championship.
The Ontario Junior B Lacrosse League of the Ontario Lacrosse Association has been around since at least 1965. The OJBLL compete for the J. A. MacDonald Trophy annually at the provincial level. At the national level, the OJBLL has been extremely dominant at the Founders Cup tournament only losing out to other leagues a handful of times in the last 40+ years.
Clarington Green Gaels had a run between 1998 and 2004 when the Gaels won 4 Founders Cups as Canadian Junior "B" champions and 2 J. A. MacDonald Trophy OJBLL Championships. Of the recent expansion of the league, the Oakville Buzz have been the most remarkable franchise to be built. In 2006, the Buzz team went 19-1 and strolled through the playoffs with little opposition. The Buzz went undefeated at the Founders Cup and crushed the hopes of the host Windsor AKO Fratmen, beating them by a score of 10-4 in the final.
Currently, the league is dominated by the Six Nations Rebels, winners of five of the past seven league championships and Founders Cups (2007, 2008, 2011, 2012, and 2013).