 Educated at Cistercian College, Roscrea and NUI Galway (where he studied commerce), he first played for Ireland at Schools level in 1998 and at Under-21 level before he was brought into their senior side during the 2000–01 season.He is also a graduate of the sports college, Setanta College.Duffy played for the amateur clubs Ballina RFC, his hometown's side and Galway city-based Galwegians RFC, before playing for his native province of Connacht.