More than 65,000 Junior Certificate students celebrated their results in traditional fashion last night, with many ignoring calls to avoid alcohol.
Fights broke out at a number of locations in Dublin, the worst in Tallaght, where up to 2,000 teenagers congregated outside a disco at Belgard Road. Gardai were forced to break up a number of arguments and three boys were arrested and later released into the custody of their parents.
Three units of Dublin Fire Brigade were also called to the scene to remove a number of teenagers to Tallaght Hospital to be treated for excess alcohol consumption.
Gardai in Ranelagh were called to break up a mini-riot at Chelmsford Road just before 11 p.m. A teenage girl was taken to hospital after being struck in the face by a glass.
Some commuters reported under-age drinking and disorderly behaviour on buses and DART trains, while residents in Killiney complained of students gathering at the local beach after midnight to drink cans of beer.
There were minor disturbances in Donnybrook. Garda Alan O'Sullivan, who was patrolling the area, said that fighting between pupils from rival schools had been the main cause of the trouble.
Problems were averted in many areas by schools organising special non-alcohol discos for their students.
It was a stressful night for parents waiting to collect their teenage sons and daughters outside discos, some of which did not close until after 1 a.m.
"I came down just to check there wasn't any alcohol", said Mr Seamus Conaty, from Dundrum, who had dropped his son, James, to a disco in Donnybrook only to find he could not get in without a ticket.
Mr Conaty said he was disappointed that his son's school had organised nothing for the students.
A number of students said that a shortage of tickets for discos had led to fights, while others claimed that students were being mugged for tickets and money, as they were seen as easy targets.
"We got robbed on the bus by a few guys in their twenties", said Peter Delaney, from Ballinteer Community College, who was stranded in Donnybrook with a friend.
Earlier yesterday, the Vintners Federation of Ireland warned about under-age drinking in the aftermath of the results, saying that the problem highlighted the need for a mandatory national identity card scheme which would make it easier for publicans to confirm the ages of individuals.
No major incidents had been reported in Cork, Galway or Limerick by 1 a.m.