The Witnness festival was getting under way today with acts including Coldplay, David Gray and the Manic Street Preachers playing to thousands in Co Kildare.
Some 25,000 revellers a day are expected at the two-day festival, Ireland's only multi-stage weekend event.
Warm sunshine greeted music fans to Punchestown racecourse when it opened its gates at midday today. Over the two-day event more than 100 artists will perform on five stages.
Organisers said this year's festival would be the biggest in its four-year history.
Among those playing today were Supergrass, the Thrills and the Sugababes, with Coldplay headlining on the main stage.
David Gray will be tomorrow's main attraction, coming after performances from bands such as The Cardigans, the Manic Street Preachers, Beth Orton and the Super Furry Animals.
Detroit rockers the White Stripes were set to play tomorrow but had to pull out when singer and guitarist Jack White fractured his hand in a car crash in the United States.
They will be replaced by US band the Flaming Lips, who played at this year's Glastonbury.
Irish acts The Frames, Gemma Hayes and Damien Rice were also on the line-up.
Gardai are urging concert-goers to arrive early in order to avoid a repeat of the severe traffic congestion caused when Eminem played at Punchestown in June.
Dublin Bus was expected carry thousands of people to the concert on its shuttle service, which was running from Parnell Square in Dublin.
Witnness was previously staged at Fairyhouse racecourse in Co Meath, moving to Punchestown only this year.
PA