O'Cuinneagain was educated at Rondebosch Boys' School before going on to study medicine at Stellenbosch University.
[1][2][3][4][5] O'Cuinneagain played rugby at various levels with University of Cape Town and then Western Province where his teammates included, among others, Tiaan Strauss, Corné Krige and Bobby Skinstad.
However his career was initially hindered by a serious hip injury and in 1997 he left South Africa and moved to England where he joined Sale Sharks.
He played in all four games during the 1999 Five Nations Championship and then captained Ireland on both a tour of Australia and during the 1999 Rugby World Cup.
He made his final appearance for Ireland in a 60–13 win against Italy at Lansdowne Road on 2 March 2000.
[16][17][18] After retiring as a rugby player, O'Cuinneagain returned to Cape Town to work as a doctor.