One man dressed as St. Patrick in papal hat and sunglasses did the samba, while another float nearby featured "Miss Panty," Dublin's premier drag queen.
Dublin's freewheeling parade drew a half-million spectators and included Christine Quinn, the first openly gay leader of the New York City Council.
Quinn is boycotting the more conservative New York parade because the organizers refuse to let gay and lesbian groups march.
This year, she accepted an Irish government invitation to be part of the Dublin City Council contingent.
"The fact I'm here in Dublin and able to march and participate in inclusive events should send a message of how backwards the New York parade is," said Quinn.
The Irish economy has been booming for the past 13 years, drawing immigrants from around the world to the country - and its festivities.
"Nowadays there's far more color in the parade. It's great to see all our new Irish from across the world dressed up in green," said Prime Minister Bertie Ahern, who normally spends St. Patrick's Day in the United States but returned overnight after visiting President Bush in the White House.
The parade also featured about a dozen high school and college bands from the United States.
The leader of Ireland's 4 million Roman Catholics, Archbishop Sean Brady, appealed to Ireland to remember the religious roots of the holiday in this rapidly secularizing land.
"The challenge for all of us is to be consistent and coherent, not just in honoring Patrick with our lips and our parades, but with our hearts and lives - to honor what he really represents by earnestly trying to embody it in our own lives," Brady said.
More than 1,000 police were on duty to deal with expected alcohol-fueled trouble in the evening, following widespread drunkenness that led to 700 arrests in 2005 and lesser trouble last year.
Dublin liquor stores were ordered closed until 4 p.m. to deter public drinking until well after the parade concluded.
This was the first St. Patrick's Day period when police have been empowered to breathalyze drivers randomly on road checkpoints - a new law that resulted in 60 arrests in the hours before the parade.