One of the most famous warm-up acts in the country, the Artane Boys Band, kicked off the Oxegen music festival in Co. Kildare in the past hour.
They will be followed on the main stage by Dublin band the Coronas while Blur will take to the stage just after 11pm tonight.
30,000 people camped out at the Punchestown Racecourse last night and there were no reports of any serious trouble.
There were however 12 arrests made for public order and drug related offences.
Superintendent John Gilligan said Gardaí will be taking any trouble very seriously.