Britain's royal family was gathered at Sandringham Estate, a traditional royal gathering spot, when Philip experienced chest pains, according to media reports. The prince, husband to Queen Elizabeth II, turned 90 in June.
Philip was visited on Saturday by family members including his wife of 64 years, sons Prince Charles, Prince Andrew and Prince Edward and daughter Princess Anne, according to the BBC. Agence France-Presse said Charles' wife, Camilla, also was among the visitors.
A Buckingham Palace spokesman told AFP that the "Duke of Edinburgh had a good night."
Philip's illness marred the celebration of what was the former Kate Middleton's first Christmas as a royal and, according to ABC News, the biggest gathering of the British royal family in years.
Twenty-seven family members were expected over the holiday weekend at the 20,000-acre Sandringham estate in eastern England.
Duchess Catherine recently attended her first traditional Christmas lunch, which is hosted by the queen for about 50 family members. Philip also attended Monday's event at Buckingham Palace.
It seemed likely Saturday that Philip would remain hospitalized over the holiday, Reuters said, missing the traditional Christmas Eve exchange of gifts among members of the royal family.
The procedure that the Duke of Edinburgh underwent is considered "minimally invasive," Buckingham Palace said in a statement. It's typically done through a catheter, with a balloon inserted into the blocked artery. The balloon is inflated and then a stent inserted to keep the artery wall open. It can be performed under local anaesthetic.
-- Amy Hubbard
Photo: Queen Elizabeth II and husband Prince Philip at the Berlin airport in 2000. Credit: Markus Schreiber / Associated Press