Four of the men are aged in their 20s and one is aged in his teens.
They are currently detained under Section 4 of the Criminal Justice Act, 1984 at a number of Tipperary Garda stations.
It comes after a man in his 20s was seriously assaulted on the evening of June 27th in Upperchurch Village.
He was taken to Cork University Hospital where he was treated for serious injuries.
Gardaí at Thurles had appealed for any witnesses to the assault to come forward.