The Medallion Shield is an annual rugby union competition involving schools affiliated to the Ulster Branch of the Irish Rugby Football Union. The competition is open to all schools within Ulster, but only schools from within Northern Ireland currently enter, with no entries from schools situated in the three Ulster counties within the Republic of Ireland.

The competition has been contested continuously since its inception in 1910 and, in that time, fourteen different schools have secured at least a shared win of the shield. Teams entering the Medallion Shield are composed of boys who are under 15 years of age at the start of the school year. Entry in 2012-13 stood at 38 schools.

Campbell College, Belfast, has won 5 outright, most recently being the 2022 season.

The 2023 competition resulted in a final between Ballymena Academy and Royal Belfast Academical Institution with RBAI winning 10-7.RBAI have now won the competition 35 times outright and shared it 3 times.