In the late 1990s, McGuinness represented Ireland as a scrum-half in 14 Test matches, debuting against the All Blacks at Lansdowne Road in 1997.[2] He was widely regarded as the best player on field in Ireland's two-point loss to France in Paris during the 1998 Five Nations Championship.[3] His run as Ireland's scrum-half ended in 1999 when he lost his place in the side to Tom Tierney, only a few months before that year's Rugby World Cup.[4]
McGuinness's career was hampered by a serious foot injury which required multiple operations.[5]